JP7483505B2 - Compound gear, cartridge, image forming apparatus, molding die, and method for manufacturing compound gear - Google Patents

Compound gear, cartridge, image forming apparatus, molding die, and method for manufacturing compound gear Download PDF

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JP7483505B2
JP7483505B2 JP2020095174A JP2020095174A JP7483505B2 JP 7483505 B2 JP7483505 B2 JP 7483505B2 JP 2020095174 A JP2020095174 A JP 2020095174A JP 2020095174 A JP2020095174 A JP 2020095174A JP 7483505 B2 JP7483505 B2 JP 7483505B2
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compound gear
hole
web
rotating shaft
gear according
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学 飯島
達朗 藤井
優太 板橋
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Canon Inc
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Description

本発明は、複合歯車、カートリッジ、画像形成装置、成形型、および複合歯車の製造方法に関する。 The present invention relates to a compound gear, a cartridge, an image forming device, a molding die, and a method for manufacturing a compound gear.

樹脂製の歯車は、複写機、プリンター等のＯＡ機器、インクカートリッジ等の消耗品、デジタルカメラやビデオカメラ等の小型精密機器のような広い範囲の機械製品に動力伝達部品として組み込まれている。従来、高精度な動力伝達部品としての樹脂製歯車には歯先円寸法や噛合い誤差（日本歯車工業会規格ＪＧＭＡ １１６－０２）や歯すじ等級（ＩＳＯ１３２８を基とするＪＩＳ Ｂ １７０２）の精度規格がその用途と目的に応じて設定されている。特に、高品質な機械製品に用いられる樹脂製歯車では、これら精度規格の幅を小さく設定して品質を高めたものが多い。 Plastic gears are incorporated as power transmission parts in a wide range of mechanical products, such as office equipment such as copiers and printers, consumables such as ink cartridges, and small precision equipment such as digital cameras and video cameras. Conventionally, precision standards for plastic gears as high-precision power transmission parts, such as tooth tip circle dimensions, meshing error (Japan Gear Manufacturers Association standard JGMA 116-02), and tooth lead grade (JIS B 1702 based on ISO 1328), have been set according to their use and purpose. In particular, plastic gears used in high-quality mechanical products often have higher quality by setting the range of these precision standards narrower.

しかし、近年のカラープリンターやカラー複写機は高品質だけでなく、駆動時の低騒音性能や印字性能の高度化など機能面の向上も併せて求められるようになってきている。これらの機器の場合、従来のように歯車の精度規格幅を小さく設定する方法だけは要求を満足することが困難であり、歯車の回転伝達精度（ＪＩＳ Ｂ １７０２－３附属書 １）などの動的精度も高めることが必要になる。 However, in recent years, color printers and color copiers are required to not only be of high quality, but also to have improved functionality, such as low noise levels during operation and advanced printing performance. For these devices, it is difficult to meet these requirements using only the conventional method of narrowing the range of precision standards for gears, and it is now necessary to improve dynamic precision, such as the gear rotation transmission precision (JIS B 1702-3, Annex 1).

例えば傾斜させた歯を有する斜歯（はすば）歯車などの場合、回転伝達精度が悪化する事象として、（１）歯車歯面精度の不良、（２）歯車支持部の不良、（３）回転駆動時における歯車の変形、といった問題が知られている。 For example, in the case of helical gears with inclined teeth, problems that are known to cause deterioration in rotation transmission accuracy include (1) poor gear tooth surface accuracy, (2) defects in the gear support parts, and (3) deformation of the gear during rotational driving.

これら問題の内、（１）は、例えば歯面に与えられた規格が使用環境に適していないか、成形加工時の樹脂収縮に伴う形状悪化などに起因するものと考えられる。（２）は例えば歯車の支持軸が回転軸に対して偏芯あるいは傾いていることにより生じると考えられる。（３）は歯車を実際に機械製品に組み込み、特定の回転速度で回転させたときに発生するトルクなどによって引き起こされる、と考えられる。上記の（１）、（２）の場合では、歯車に対して歯すじ誤差精度（ＪＩＳ Ｂ １７０２）や同軸度などの諸規格を設定し、その規格に収まる歯車を採用することで管理することが可能である。一方、（３）は歯車の動的環境によって生じる問題のため、（１）、（２）のような静的環境下における精度規格では回避するのが難しい場合がある。 Of these problems, (1) is thought to be caused, for example, by the specifications given to the tooth surface not being suitable for the usage environment, or by deterioration of the shape due to resin shrinkage during molding. (2) is thought to be caused, for example, by the gear's support shaft being eccentric or tilted with respect to the rotation axis. (3) is thought to be caused by the torque generated when the gear is actually incorporated into a mechanical product and rotated at a specific rotation speed. In the above cases of (1) and (2), it is possible to manage the problem by setting various standards for the gear, such as tooth trace error accuracy (JIS B 1702) and coaxiality, and using gears that meet those standards. On the other hand, (3) is a problem caused by the dynamic environment of the gear, and may be difficult to avoid with accuracy standards in a static environment such as (1) and (2).

例えば、図１３（ａ）、（ｂ）に示すような樹脂製歯車７０は、傾斜した歯７１（はす歯）が形成された円環状のリム７２と、歯車の中心に配設された回転支持部７４とがウェブ７９で接続されている。回転支持部７４は円筒状で、内径部８１と外径部８２および８３から成る。回転支持部の構造は、機械製品の構成によって違い、内径部８１に樹脂製あるいは金属製のシャフトを嵌合させて支持する、外径部８２または８３、あるいは両方を軸受として支持する、などの構成がある。 For example, a plastic gear 70 as shown in Figures 13(a) and (b) has an annular rim 72 with inclined teeth 71 (helical teeth) formed thereon, and a rotation support part 74 disposed at the center of the gear, connected by a web 79. The rotation support part 74 is cylindrical and consists of an inner diameter part 81 and outer diameter parts 82 and 83. The structure of the rotation support part varies depending on the configuration of the mechanical product, and can be configured such that a plastic or metal shaft is fitted and supported in the inner diameter part 81, or the outer diameter parts 82 and/or 83 are supported as bearings.

通常、このような樹脂製歯車７０を回転駆動させるとトルクが発生するため回転支持部７４にねじりモーメントが生じる。また、樹脂製歯車７０が傾斜した歯７１を有する場合では、歯のねじれ成分によってスラスト方向へ分力が発生する。つまり複数の力成分が回転支持部の軸周りで発生することになる。 Normally, when such a resin gear 70 is rotated, a torque is generated, which generates a torsional moment in the rotation support part 74. Furthermore, if the resin gear 70 has inclined teeth 71, a component force is generated in the thrust direction due to the torsional component of the teeth. In other words, multiple force components are generated around the axis of the rotation support part.

従来、この種の樹脂製歯車はポリアセタールなどの摺動性が良く、機械的強度が大きい樹脂材料を用いて形成されていた。しかし、近年の機械製品の高機能化などにより樹脂製歯車にかかる力が大きくなり、回転支持部への負荷が増大しているため変形が度々問題となっている。そこで、近年では回転支持部を高剛性な合成樹脂で形成し、歯車は従来通りのポリアセタール等で形成した複合歯車が提案されている。 Traditionally, this type of plastic gear has been made from a plastic material such as polyacetal, which has good sliding properties and high mechanical strength. However, in recent years, the increasing functionality of mechanical products has placed greater forces on plastic gears, and the load on the rotation support parts has increased, causing frequent deformation problems. As a result, compound gears have been proposed in recent years, in which the rotation support parts are made from highly rigid synthetic resins and the gears are made from conventional materials such as polyacetal.

例えば、図１４（ａ）、（ｂ）、図１５（ａ）～（ｃ）は、二種類の材料で形成された複合歯車４０の従来構成を示している。この複合歯車４０は、高剛性な合成樹脂で形成された回転支持部６１を有する第１の部材６０（図１４（ａ））と、歯部９１を含む第２の部材９０（図１４（ａ）、図１５（ａ）～（ｃ））から成る。第２の部材９０は、前記第１の部材よりも柔らかい合成樹脂から形成され、前記第１の部材の外周を覆うよう第１の部材６０と一体化される。 For example, Figures 14(a), (b) and 15(a)-(c) show a conventional configuration of a compound gear 40 made of two types of materials. This compound gear 40 is made of a first member 60 (Figure 14(a)) having a rotation support portion 61 made of a highly rigid synthetic resin, and a second member 90 (Figures 14(a), 15(a)-(c)) including a tooth portion 91. The second member 90 is made of a synthetic resin that is softer than the first member, and is integrated with the first member 60 so as to cover the outer periphery of the first member.

図１４（ａ）、（ｂ）、図１５（ａ）～（ｃ）の複合歯車４０において、第１の部材６０の回転支持部６１は内径穴６２と外径部６３および６４を有する。また、回転支持部６１の外周側には第２の部材で覆われる内側ウェブ６５が配設されている。第２の部材９０には、図１５（ｂ）、（ｃ）に示すように前記内側ウェブ６５を覆う外側ウェブ９２が配設されている。このように、第１の部材６０を高剛性材料から形成することにより回転駆動時に発生するねじりモーメントやスラスト分力による変形を抑制することができ、前述した（３）の問題を最小限に留めることができる。さらに、第２の部材９０に摺動性の良い合成樹脂を用いることで歯車に必要な回転潤滑性も得られる。 In the compound gear 40 of Fig. 14 (a), (b) and Fig. 15 (a) to (c), the rotation support part 61 of the first member 60 has an inner diameter hole 62 and outer diameter parts 63 and 64. In addition, an inner web 65 covered by the second member is arranged on the outer periphery of the rotation support part 61. As shown in Fig. 15 (b) and (c), an outer web 92 that covers the inner web 65 is arranged on the second member 90. In this way, by forming the first member 60 from a highly rigid material, it is possible to suppress deformation due to the torsional moment and thrust force generated during rotational driving, and the above-mentioned problem (3) can be minimized. Furthermore, by using a synthetic resin with good sliding properties for the second member 90, the rotational lubrication required for gears can be obtained.

このような複合歯車４０は、第１の部材６０による回転支持部と、第２の部材９０の歯車部は強固に結合していなければならない。従来では、第１の部材６０と第２の部材９０を別々に製作し、その後、締結や圧入で両者を組み合わせる製造方法が用いられることがあった。しかし、この手法では、組み付け時の誤差によって精度が低下しやすく、さらに製造に伴う装置、部品、労働力、時間も余分に必要となる問題があった。 In such a compound gear 40, the rotation support portion of the first member 60 and the gear portion of the second member 90 must be firmly connected. Conventionally, a manufacturing method has been used in which the first member 60 and the second member 90 are manufactured separately and then combined by fastening or press-fitting. However, this method has the problem that accuracy is easily reduced due to errors during assembly, and additional equipment, parts, labor, and time are required for manufacturing.

そこで、他の製造方法として、第１の部材を金型にインサートし第２の部材を射出成形することで二つの部材を完全に密着させる方法が提案されている。この手法によると、第１の部材と第２の部材に相溶性が無いと剥離してしまう可能性があるため、図１４（ａ）、（ｂ）、図１５（ａ）～（ｃ）の複合歯車のように第１の部材を第２の部材で挟持させる構造を取る。また、回転時に生じるトルクで位相ずれが生じないように、第１の部材の内側ウェブ６５の最外周に凹凸部６７を付加して回転方向の密着強度も確保する。いずれにしても、この種の複合歯車はスラスト方向と回転方向両方の密着強度が必要となる。 As a result, another manufacturing method has been proposed in which the first component is inserted into a mold and the second component is injection molded to completely bond the two components together. With this method, if the first and second components are not compatible, there is a risk of them peeling off, so a structure is adopted in which the first component is sandwiched between the second component, as in the compound gears of Figures 14(a), (b) and Figures 15(a) to (c). Also, to prevent phase shifts due to the torque generated during rotation, uneven parts 67 are added to the outermost circumference of the inner web 65 of the first component to ensure adhesion strength in the rotational direction. In any case, compound gears of this type require adhesion strength in both the thrust and rotational directions.

例えば、特許文献１では軸方向に凹溝を有したインサート部材の外周に合成樹脂からなる歯部を一体成形し、剛性と精度を両立させる構成が提案されている。また、特許文献２では凹凸部が形成された円盤部が回転軸に設けられ、歯車をこの円盤部全体を覆うように成形し、回転軸と歯車間の固着強度を向上させる構成が提案されている。また、特許文献３では樹脂製歯車の側面に設けられた凸部と金属板側面に設けられた穴部とを係合させることにより、剛性を確保する構成が提案されている。 For example, Patent Document 1 proposes a configuration in which teeth made of synthetic resin are molded integrally with the outer periphery of an insert member having an axial groove, achieving both rigidity and precision. Patent Document 2 proposes a configuration in which a disk portion with projections and recesses is provided on a rotating shaft, and a gear is molded to cover the entire disk portion, improving the adhesion strength between the rotating shaft and the gear. Patent Document 3 proposes a configuration in which a projection on the side of a resin gear engages with a hole on the side of a metal plate, ensuring rigidity.

特開２０１０－１３９０４１号公報JP 2010-139041 A 特開２００３－２１２２４号公報JP 2003-21224 A 実開平４－１２４６２８号公報Japanese Utility Model Application Publication No. 4-124628

しかしながら、上記のような複数の異種材料からなる複合歯車は部材間の結合を強固にするほど、寸法変化による割れの発生が問題になることがある。この種の製品において、歯車部は摺動性のよいポリアセタールなどの結晶性樹脂で製造されることが多い。例えばポリアセタールのような結晶性樹脂は摺動性を得やすい反面、成形後も分子の結晶化が進み続けるため、経時収縮量が大きい。そのため、この種の結晶性樹脂を歯車部に用いた複合歯車は、収縮量の違いから歪が生じやすくなる傾向がある。例えば、図１４（ａ）、（ｂ）、図１５（ａ）～（ｃ）に示すような複合歯車では、回転軸部を構成する第１の部材６０にポリブタジエンテレフタレートなどを用いた繊維強化樹脂を、第２の部材９０にポリアセタール樹脂を使用する場合がある。その場合、ポリアセタール樹脂の収縮率が１．６～２．０％であるのに対して、ポリブタジエンテレフタレートなどを用いた繊維強化樹脂では収縮率は０．２～０．８％程度、と大きく異なる。このため、図１４および１５の構造では、第１の部材６０の内側ウェブ６５を覆うように第２の部材９０の外側ウェブ９２が形成されているため、第１の部材６０が第２の部材９０の収縮を阻害する関係が形成される。そして、上記のような材質選定によると、第２の部材９０の機械的強度のほうが、第１の部材６０よりも弱いため経時収縮が進むと第２の部材９０で歪が大きくなって、割れが発生することがある。 However, in compound gears made of multiple different materials as described above, the stronger the bond between the components, the more likely it is that cracks will occur due to dimensional changes. In this type of product, the gear part is often made of crystalline resin such as polyacetal, which has good sliding properties. For example, crystalline resins such as polyacetal are easy to obtain sliding properties, but the molecular crystallization continues even after molding, so the amount of shrinkage over time is large. Therefore, compound gears using this type of crystalline resin for the gear part tend to be easily distorted due to the difference in the amount of shrinkage. For example, in compound gears such as those shown in Figures 14 (a), (b), and 15 (a) to (c), a fiber-reinforced resin using polybutadiene terephthalate or the like may be used for the first member 60 constituting the rotating shaft part, and a polyacetal resin may be used for the second member 90. In this case, the shrinkage rate of polyacetal resin is 1.6 to 2.0%, while the shrinkage rate of fiber-reinforced resin using polybutadiene terephthalate or the like is about 0.2 to 0.8%, which is a large difference. For this reason, in the structure of Figures 14 and 15, the outer web 92 of the second member 90 is formed so as to cover the inner web 65 of the first member 60, creating a relationship in which the first member 60 inhibits the shrinkage of the second member 90. And, with the above-mentioned material selection, the mechanical strength of the second member 90 is weaker than that of the first member 60, so as shrinkage progresses over time, distortion in the second member 90 increases, which may cause cracks.

通常、経時収縮は、常温の生活環境下では比較的ゆっくりと進むため、割れが生じるのに数十年から数百年を要し問題になる可能性は低い。しかしながら、歯車が用いられる機器によっては、周囲温度が高い環境で使用される場合があり、その場合には経時収縮の速度が加速され、数年で割れが生じることがある。 Normally, shrinkage over time progresses relatively slowly in normal temperature living environments, so it takes decades or even centuries for cracks to occur, making it unlikely to become a problem. However, some equipment using gears may be used in environments with high ambient temperatures, in which case the rate of shrinkage over time accelerates and cracks may occur within a few years.

上記の特許文献１は、軸方向に凹溝を有したインサート部材の外周に合成樹脂からなる歯部を一体成形することで剛性と精度を両立させる構成を提案しているが、二つの材料の収縮差によって生じる歪の抑制に関する対策は行われていない。 The above-mentioned Patent Document 1 proposes a configuration that achieves both rigidity and precision by integrally molding a tooth portion made of synthetic resin onto the outer periphery of an insert member that has an axial groove, but does not take measures to suppress distortion caused by the difference in shrinkage between the two materials.

特許文献２は、凹凸部が形成された円盤部が回転軸に設けられ、歯車をこの円盤部全体を覆うように成形し、回転軸と歯車間の固着強度を向上させる構成を提案しているが、やはり収縮差による歪の抑制に関する対策は行われていない。 Patent Document 2 proposes a configuration in which a disk portion with projections and recesses is provided on a rotating shaft, and a gear is molded to cover the entire disk portion, improving the adhesion strength between the rotating shaft and the gear, but again, no measures are taken to suppress distortion caused by differential shrinkage.

また、特許文献３は、樹脂製歯車の側面に設けられた樹脂製歯車の側面に設けられた凸部と金属板側面に設けられた穴部とを係合させることにより、剛性を確保する構成を提案している。そして、この凸部と、穴部との係合部にクリアランスを設定することによって経時収縮の割れを抑制することが開示されている。しかしながら、剛性確保用の金属板金は樹脂材平面部の片側面に設置されているだけで、スラスト方向には強固に結合しているとは言い難く、クリアランスがあることが相まって使用時に両者が分離する可能性がある。以上のように、従来技術では、歯車を異種材料からなる２部材で構成する場合、これら２部材間の結合力確保と収縮差から生じる割れの抑制の両立は困難であった。 Patent Document 3 also proposes a configuration that ensures rigidity by engaging a protrusion on the side of the resin gear with a hole on the side of the metal plate. It also discloses that cracks caused by shrinkage over time are suppressed by setting a clearance at the engagement between the protrusion and the hole. However, the metal plate for ensuring rigidity is only installed on one side of the flat part of the resin material, and it is difficult to say that it is firmly bonded in the thrust direction, and the presence of a clearance means that the two may separate during use. As described above, in the prior art, when a gear is constructed from two members made of different materials, it was difficult to ensure the bonding force between these two members and suppress cracks caused by shrinkage differences.

本発明の課題は、上記の問題に鑑み、経時収縮による割れなどの破損の可能性を低減できる複合歯車、カートリッジ、画像形成装置、成形型、および複合歯車の製造方法を提供することにある。 In view of the above problems, the present invention aims to provide a compound gear, a cartridge, an image forming device, a molding die, and a method for manufacturing a compound gear that can reduce the possibility of damage such as cracking due to shrinkage over time.

本発明の一態様は、回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材と、外周に少なくとも一つ以上の噛合歯を有し、前記ウェブに支持されて前記第１の部材の外周を囲むように設けられている第２の部材と、を備えた複合歯車であって、前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように形成されている、複合歯車である。 One aspect of the present invention is a compound gear comprising a first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion, and a second member having at least one meshing tooth on its outer periphery, supported by the web, and arranged to surround the outer periphery of the first member, wherein the outermost peripheral surface of the first member has a radial space between it and the second member, the innermost peripheral surface of the second member has a radial space between it and the first member, and at least one of the first member and the second member is formed so as to sandwich the other of the first member and the second member from both axial sides of the rotating shaft portion.

本発明の他の一態様は、複合歯車の製造に用いられる成形型において、前記複合歯車は、回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材と、外周に少なくとも一つ以上の噛合歯を有し、前記ウェブに支持されて前記第１の部材の外周を囲むように設けられている第２の部材と、を備え、前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように形成されており、前記成形型は、第１の固定金型と、第２の固定金型と、移動金型と、を有し、前記移動金型が前記第１の固定金型に対向している状態で前記第１の部材が成形され、前記第１の部材が成形された後に前記移動金型が前記第２の固定金型に対向する位置に移動した状態で、前記第１の部材と一体になるように前記第２の部材が成形されるように構成されている、成形型である。 In another aspect of the present invention, in a molding die used for manufacturing a compound gear, the compound gear comprises a first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion, and a second member having at least one meshing tooth on its outer periphery, supported by the web and disposed so as to surround the outer periphery of the first member, wherein an outermost peripheral surface of the first member has a radial space between it and the second member, and an innermost peripheral surface of the second member has a radial space between it and the first member, and at least one of the first member and the second member is formed to sandwich the other of the first member and the second member from both sides in the axial direction of the rotating shaft portion, and the molding die has a first fixed die, a second fixed die, and a movable die, and is configured so that the first member is molded with the movable die facing the first fixed die, and after the first member is molded, the movable die moves to a position facing the second fixed die, and the second member is molded to be integrated with the first member.

本発明のさらに他の一態様は、回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材を成形する第１の工程と、第１の工程で成形された前記第１の部材を成形型に収容し、外周に少なくとも一つ以上の噛合歯を有する第２の部材を、前記ウェブに支持されて前記第１の部材の外周を囲むように形成する第２の工程と、を含み、前記第２の工程において、前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように、前記第２の部材を形成する複合歯車の製造方法である。 Yet another aspect of the present invention is a manufacturing method for a compound gear including a first step of molding a first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion, and a second step of housing the first member molded in the first step in a molding die and forming a second member having at least one meshing tooth on its outer periphery supported by the web to surround the outer periphery of the first member, wherein in the second step, the second member is formed such that an outermost peripheral surface of the first member has a radial space between it and the second member, an innermost peripheral surface of the second member has a radial space between it and the first member, and at least one of the first member and the second member holds the other of the first member and the second member from both axial sides of the rotating shaft portion.

本発明によれば、経時収縮による割れなどの破損の可能性を低減できる。 The present invention reduces the possibility of damage such as cracks caused by shrinkage over time.

実施形態に係る複合歯車を示したもので、（ａ）は回転軸部を構成する第１の部材の斜視図、（ｂ）は外周に噛合歯を備えた第２の部材を含む複合歯車全体の斜視図である。1A is a perspective view of a first member constituting a rotating shaft portion, and FIG. 1B is a perspective view of the entire compound gear including a second member having meshing teeth on its outer periphery. FIG. （ａ）～（ｃ）は実施形態に係る複合歯車の構成を示した説明図である。5A to 5C are explanatory diagrams showing the configuration of a compound gear according to an embodiment. （ａ）～（ｃ）は実施形態に係る複合歯車の構成を示した説明図である。5A to 5C are explanatory diagrams showing the configuration of a compound gear according to an embodiment. （ａ）、（ｂ）は実施形態に係る複合歯車を形成する成形型の構成および動作を示した説明図である。5A and 5B are explanatory views showing the configuration and operation of a molding die for forming a compound gear according to an embodiment. （ａ）～（ｃ）は実施形態に係る複合歯車の収縮後の状態を示した説明図である。5A to 5C are explanatory diagrams showing a state after contraction of the compound gear according to the embodiment. （ａ）～（ｃ）は実施形態に係る複合歯車の収縮後の状態を示した説明図である。5A to 5C are explanatory diagrams showing a state after contraction of the compound gear according to the embodiment. （ａ）～（ｃ）は実施例２に係る複合歯車の構成を示した説明図である。5A to 5C are explanatory diagrams showing the configuration of a compound gear according to a second embodiment. （ａ）～（ｃ）は実施例３に係る複合歯車の構成を示した説明図である。11A to 11C are explanatory diagrams showing the configuration of a compound gear according to a third embodiment. （ａ）～（ｃ）は実施例４に係る複合歯車のゲート痕の位置を示した説明図である。10A to 10C are explanatory views showing positions of gate marks of a compound gear according to a fourth embodiment. （ａ）、（ｂ）は実施例５に係る複合歯車の構成を示した説明図である。10A and 10B are explanatory diagrams showing a configuration of a compound gear according to a fifth embodiment. （ａ）～（ｃ）は実施例６に係る複合歯車の構成を示した説明図である。13A to 13C are explanatory diagrams showing the configuration of a compound gear according to a sixth embodiment. （ａ）、（ｂ）は実施例７に係る複合歯車を形成する成形型の構成および動作を示した説明図である。13A and 13B are explanatory views showing the configuration and operation of a molding die for forming a compound gear according to Example 7. （ａ）、（ｂ）は従来の一種類の合成樹脂で形成された歯車の構成を示した説明図である。1A and 1B are explanatory diagrams showing the configuration of a conventional gear made of one type of synthetic resin. 従来の歯車において、（ａ）は回転軸部を構成する第１の部材の斜視図、（ｂ）は外周に噛合歯を備えた第２の部材を含む歯車全体の斜視図である。In a conventional gear, (a) is a perspective view of a first member constituting a rotating shaft portion, and (b) is a perspective view of the entire gear including a second member having meshing teeth on its outer periphery. （ａ）～（ｃ）は従来の複合歯車の構成を示した説明図である。1A to 1C are explanatory diagrams showing the configuration of a conventional compound gear. （ａ）は従来の複合歯車の収縮時に生じる応力分布を示した説明図、（ｂ）は実施形態に係る複合歯車の収縮時に生じる応力分布を示した説明図である。FIG. 4A is an explanatory diagram showing stress distribution occurring when a conventional compound gear is contracted, and FIG. 4B is an explanatory diagram showing stress distribution occurring when a compound gear according to an embodiment is contracted. 実施形態に係る複合歯車が回転駆動時に生じる応力分布を示した説明図である。FIG. 4 is an explanatory diagram showing a stress distribution generated when the compound gear according to the embodiment is driven and rotated. 実施形態に係るカートリッジを用いた画像形成装置の構成を示した説明図である。FIG. 1 is an explanatory diagram illustrating a configuration of an image forming apparatus using a cartridge according to an embodiment. 実施形態に係るカートリッジの構成を示した斜視図である。FIG. 2 is a perspective view showing a configuration of a cartridge according to the embodiment. （ａ）、（ｂ）は実施形態に係る複合歯車の変形例を示した説明図である。5A and 5B are explanatory diagrams showing modified examples of the compound gear according to the embodiment. （ａ）～（ｃ）は実施形態に係る複合歯車の変形例を示した説明図である。5A to 5C are explanatory diagrams showing modified examples of the compound gear according to the embodiment. （ａ）～（ｃ）は実施形態に係る複合歯車の変形例を示した説明図である。5A to 5C are explanatory diagrams showing modified examples of the compound gear according to the embodiment. （ａ）～（ｇ）は実施形態に係る複合歯車の変形例を示した説明図である。5A to 5G are explanatory diagrams showing modified examples of the compound gear according to the embodiment.

以下、添付図面を参照して本発明を実施するための形態につき説明する。なお、以下に示す構成はあくまでも一例であり、例えば細部の構成については本発明の趣旨を逸脱しない範囲において当業者が適宜変更することができる。また、本実施形態で取り上げる数値は、可能な数値設定の一例である。 Below, a description will be given of an embodiment of the present invention with reference to the attached drawings. Note that the configuration shown below is merely an example, and those skilled in the art can appropriately change the detailed configuration, for example, without departing from the spirit of the present invention. Also, the numerical values used in this embodiment are an example of possible numerical settings.

図１（ａ）～図４（ｂ）は本実施形態の複合歯車、および複合歯車を成形する成形型（金型）の構成を示している。このうち、図１（ａ）～図３（ｃ）は本実施形態の複合歯車１０の構成を示している。図１（ａ）は、複合歯車１０（図１（ｂ））の回転軸部を構成する第１の部材５０の斜視図の形式で示している。図２（ｂ）は、図２（ａ）（複合歯車１０の上面図）のＡ－Ａ線の断面矢視に相当し、複合歯車１０の回転支持部５１の中心軸に対して平行な断面を示している。図２（ｃ）は、図２（ｂ）の一点鎖線で示した円内の断面構造を詳細に示している。図３（ｂ）は、図３（ａ）（複合歯車１０の側面図）のＢ－Ｂ線の断面矢視に相当し、図３（ｃ）は、図３（ｂ）の一点鎖線で示した円内の断面構造を詳細に示している。 Figures 1(a) to 4(b) show the configuration of the compound gear of this embodiment and the molding die (metal mold) for molding the compound gear. Of these, Figures 1(a) to 3(c) show the configuration of the compound gear 10 of this embodiment. Figure 1(a) shows in the form of a perspective view the first member 50 constituting the rotating shaft part of the compound gear 10 (Figure 1(b)). Figure 2(b) corresponds to the cross-sectional view of line A-A in Figure 2(a) (top view of the compound gear 10) and shows a cross section parallel to the central axis of the rotation support part 51 of the compound gear 10. Figure 2(c) shows in detail the cross-sectional structure within the circle indicated by the dashed line in Figure 2(b). Figure 3(b) corresponds to the cross-sectional view of line B-B in Figure 3(a) (side view of the compound gear 10), and Figure 3(c) shows in detail the cross-sectional structure within the circle indicated by the dashed line in Figure 3(b).

また、図１９は本実施形態の複合歯車を利用する画像形成用のカートリッジ１０２０の構成を、図１８は図１９のカートリッジ１０２０を着脱して用いる画像形成装置１０１０の構成を示している。本実施形態の複合歯車は、例えばカートリッジ１０２０の伝達部材１００（図１９）の部分に、用いられる。本実施形態の複合歯車は、駆動軸１００２を介して画像形成装置本体１００１側の動力をカートリッジ１０２０内の機構に伝達するよう配置される。以下では、まず図１８、図１９を参照して、画像形成装置１０１０およびカートリッジ１０２０の構成と動作につき説明しておく。 Figure 19 shows the configuration of an image forming cartridge 1020 that uses the compound gear of this embodiment, and Figure 18 shows the configuration of an image forming device 1010 that uses the cartridge 1020 of Figure 19 by attaching and detaching it. The compound gear of this embodiment is used, for example, in the transmission member 100 (Figure 19) of the cartridge 1020. The compound gear of this embodiment is arranged to transmit the power of the image forming device main body 1001 to a mechanism inside the cartridge 1020 via the drive shaft 1002. Below, the configuration and operation of the image forming device 1010 and cartridge 1020 will be described first with reference to Figures 18 and 19.

図１８に示すように、画像形成装置１０１０は、電子写真方式を採用するフルカラープリンタである。画像形成装置１０１０は、画像形成部１０１１と、シートＳを搬送する搬送部１０１２とを備える。画像形成機構としての画像形成部１０１１は、複数（本実施形態では４個）のカートリッジ１０２０を中間転写ベルト１０２７の走行方向に並べた、所謂タンデム型の構成を有する。各カートリッジ１０２０は、イエロー、マゼンタ、シアン、ブラックのトナー像をそれぞれ形成する画像形成装置用のプロセスカートリッジである。 As shown in FIG. 18, the image forming apparatus 1010 is a full-color printer that employs an electrophotographic system. The image forming apparatus 1010 includes an image forming unit 1011 and a conveying unit 1012 that conveys a sheet S. The image forming unit 1011, which serves as an image forming mechanism, has a so-called tandem configuration in which multiple cartridges 1020 (four in this embodiment) are arranged in the running direction of an intermediate transfer belt 1027. Each cartridge 1020 is a process cartridge for the image forming apparatus that forms yellow, magenta, cyan, and black toner images, respectively.

画像形成装置本体１００１には、複数のカートリッジ１０２０が着脱可能に装着される。ここで、各カートリッジ１０２０の構成は同様であるため、以下、図１８中の左端のカートリッジ１０２０について説明し、他のカートリッジについては、符号及び説明を省略する。 Multiple cartridges 1020 are removably mounted in the image forming apparatus main body 1001. Since each cartridge 1020 has the same configuration, the following will describe the cartridge 1020 on the left side in FIG. 18, and the reference numbers and descriptions of the other cartridges will be omitted.

カートリッジ１０２０は、感光ドラム１０２１、帯電ローラ１０２２、現像装置１０２３、ドラムクリーナ１０２４を備えている。感光ドラム１０２１は、画像形成装置本体１００１に配置された不図示のドラムモータによって、所定のプロセススピードで回転駆動される。感光ドラム１０２１の表面は、帯電ローラ１０２２により均一に帯電される。帯電された感光ドラム１０２１の表面には、スキャナユニット１０２５により、画像情報に基づいてレーザービームが照射されることで静電潜像が形成される。感光ドラム１０２１上の静電潜像は、現像装置１０２３によりトナーを付着させてトナー像として現像される。感光ドラム１０２１上のトナー像は、一次転写ローラ１０２６と感光ドラム１０２１との間に一次転写バイアスが印加されることで、中間転写ベルト１０２７に一次転写される。転写後に感光ドラム１０２１に残った転写残トナーは、ドラムクリーナ１０２４により除去される。 The cartridge 1020 includes a photosensitive drum 1021, a charging roller 1022, a developing device 1023, and a drum cleaner 1024. The photosensitive drum 1021 is rotated at a predetermined process speed by a drum motor (not shown) disposed in the image forming apparatus main body 1001. The surface of the photosensitive drum 1021 is uniformly charged by the charging roller 1022. An electrostatic latent image is formed on the charged surface of the photosensitive drum 1021 by irradiating the surface with a laser beam based on image information by the scanner unit 1025. The electrostatic latent image on the photosensitive drum 1021 is developed into a toner image by attaching toner to the electrostatic latent image by the developing device 1023. The toner image on the photosensitive drum 1021 is primarily transferred to the intermediate transfer belt 1027 by applying a primary transfer bias between the primary transfer roller 1026 and the photosensitive drum 1021. The residual toner remaining on the photosensitive drum 1021 after the transfer is removed by the drum cleaner 1024.

このような工程が各カートリッジ１０２０で実行されることで、各カートリッジ１０２０の感光ドラム１０２１上に形成された各色のトナー像が、中間転写ベルト１０２７上に重ねて転写され、中間転写ベルト１０２７上にフルカラーのトナー像が形成される。中間転写ベルト１０２７上のトナー像は、中間転写ベルト１０２７と二次転写ローラ１０２８とで構成される二次転写部により、搬送部１０１２により搬送されたシートＳに二次転写される。転写後に中間転写ベルト１０２７に残ったトナーは、ベルトクリーナ１０２９により除去される。 By performing such a process for each cartridge 1020, the toner images of each color formed on the photosensitive drum 1021 of each cartridge 1020 are transferred in layers onto the intermediate transfer belt 1027, forming a full-color toner image on the intermediate transfer belt 1027. The toner image on the intermediate transfer belt 1027 is secondarily transferred to the sheet S transported by the transport unit 1012 by a secondary transfer unit composed of the intermediate transfer belt 1027 and a secondary transfer roller 1028. Any toner remaining on the intermediate transfer belt 1027 after transfer is removed by a belt cleaner 1029.

搬送部１０１２は、複数の搬送ローラで構成されており、カセット１０１３に収容されたシートＳをピックアップして、画像形成部１０１１の二次転写部に搬送する。二次転写部へのシートＳの搬送は、レジストレーションローラ対１０１４により中間転写ベルト１０２７上のトナー像とタイミング合わせて行われる。二次転写部でトナー像が転写されたシートＳは、定着装置１０３０で加熱及び加圧されることでトナー像が定着される。トナー像が定着されたシートＳは、排出トレイ１０３１に排出される。 The conveying section 1012 is composed of multiple conveying rollers, and picks up the sheet S stored in the cassette 1013 and conveys it to the secondary transfer section of the image forming section 1011. The sheet S is conveyed to the secondary transfer section by a pair of registration rollers 1014 in time with the toner image on the intermediate transfer belt 1027. The sheet S onto which the toner image has been transferred in the secondary transfer section is heated and pressurized by a fixing device 1030, so that the toner image is fixed. The sheet S onto which the toner image has been fixed is discharged to a discharge tray 1031.

図１９は、第１実施形態に係る画像形成装置本体１００１に装着されるカートリッジ１０２０の斜視図である。感光ドラム１０２１は、長手方向（±Ｚ方向）に延びる例えばアルミニウムの円筒部材と、円筒部材の表面に形成された感光層とを有する。感光ドラム１０２１の長手方向の端部には、画像形成装置本体１００１の不図示のドラムモータの回転力が伝達される伝達部材１００が取り付けられている。伝達部材１００は、ユーザがカートリッジ１０２０を画像形成装置本体１００１に着脱することにより、画像形成装置本体１００１側の駆動軸１００２に係合又は係合解除するように構成されている。例えば、カートリッジ１０２０を画像形成装置本体１００１に装着する場合には、図１９中、伝達部材１００と画像形成装置本体１００１側の駆動軸１００２とを同軸に揃えながら、ユーザはカートリッジ１０２０を＋Ｚ方向に移動させて伝達部材１００を駆動軸１００２に係合させる。また、カートリッジ１０２０を画像形成装置本体１００１から取り外す場合には、図１９中、ユーザはカートリッジ１０２０を－Ｚ方向に移動させて伝達部材１００を駆動軸１００２から係合解除させる。 19 is a perspective view of the cartridge 1020 mounted in the image forming apparatus main body 1001 according to the first embodiment. The photosensitive drum 1021 has a cylindrical member, for example made of aluminum, extending in the longitudinal direction (±Z direction) and a photosensitive layer formed on the surface of the cylindrical member. A transmission member 100 to which the rotational force of a drum motor (not shown) of the image forming apparatus main body 1001 is transmitted is attached to the longitudinal end of the photosensitive drum 1021. The transmission member 100 is configured to engage or disengage with the drive shaft 1002 on the image forming apparatus main body 1001 side by a user attaching or detaching the cartridge 1020 to or from the image forming apparatus main body 1001. For example, when mounting the cartridge 1020 to the image forming apparatus main body 1001, the user moves the cartridge 1020 in the +Z direction to engage the transmission member 100 with the drive shaft 1002 on the image forming apparatus main body 1001 side while coaxially aligning the transmission member 100 and the drive shaft 1002 on the image forming apparatus main body 1001 side in FIG. 19. Furthermore, when removing the cartridge 1020 from the image forming apparatus main body 1001, in FIG. 19, the user moves the cartridge 1020 in the -Z direction to disengage the transmission member 100 from the drive shaft 1002.

再び図１（ａ）～図３（ｃ）において、本実施形態の複合歯車１０は、高剛性の樹脂で形成された第１の部材５０を備える。この第１の部材５０は、複合歯車１０の回転軸部を構成するもので、円筒形状の回転支持部５１を有する。また、複合歯車１０は、前記第１の部材よりも柔らかい合成樹脂で形成された第２の部材３０を備える。この第２の部材３０は、第１の部材５０の外周を覆い、最外周面に少なくとも歯部３１（噛合歯）を備える。本明細書において、第１の部材５０と第２の部材３０が接触している部分を接続部と称する。また、特に断らない限り、複合歯車１０に関して、「回転軸方向」は回転支持部５１の回転軸の方向を表す。「周方向」は回転支持部５１の回転軸を中心とする回転方向を表し、「放射方向radial direction」及び「内径方向inward-radial direction」は回転支持部５１の回転軸を中心とした方向を表す。 1(a) to 3(c), the compound gear 10 of this embodiment includes a first member 50 made of a highly rigid resin. The first member 50 constitutes the rotating shaft of the compound gear 10 and has a cylindrical rotating support part 51. The compound gear 10 also includes a second member 30 made of a synthetic resin that is softer than the first member. The second member 30 covers the outer periphery of the first member 50 and has at least teeth 31 (meshing teeth) on the outermost periphery. In this specification, the part where the first member 50 and the second member 30 are in contact is referred to as a connection part. Also, unless otherwise specified, the "rotation axis direction" of the compound gear 10 refers to the direction of the rotation axis of the rotation support part 51. The "circumferential direction" refers to the rotation direction centered on the rotation axis of the rotation support part 51, and the "radial direction" and the "inward-radial direction" refer to the direction centered on the rotation axis of the rotation support part 51.

図１（ａ）～図３（ｃ）に示すように、第１の部材５０の回転支持部５１は、回転軸部を構成し、内径穴５２と外径部５３（図２（ｂ））、５４を有する。回転支持部５１の外周には、第２の部材３０と結合される円盤状の内側ウェブ５５が配設される。 As shown in Figures 1(a) to 3(c), the rotation support part 51 of the first member 50 constitutes a rotation shaft part and has an inner diameter hole 52 and an outer diameter part 53 (Figure 2(b)), 54. A disk-shaped inner web 55 that is connected to the second member 30 is arranged on the outer periphery of the rotation support part 51.

本実施形態の内側ウェブ５５には、貫通穴５７が設けられている（図２（ａ）、（ｃ））。貫通穴５７は、回転支持部５１の回転軸を中心からほぼ同じ距離にある周上に複数、配置される。本実施形態では、貫通穴５７は、例えば図３（ｂ）、（ｃ）などに示すように、いわゆる扇面形状を有する。 In this embodiment, the inner web 55 is provided with through holes 57 (FIGS. 2(a) and (c)). A plurality of through holes 57 are arranged around the circumference of the rotation axis of the rotation support part 51 at approximately the same distance from the center. In this embodiment, the through holes 57 have a so-called fan shape, as shown in, for example, FIG. 3(b) and (c).

本実施形態では、貫通穴５７を画成する２つの側縁部５８、５８は、円周方向に対向し、歯車回転中心に対して放射方向ｂ１（径方向）と実質的に平行な向きを持つ。第２の部材３０は、第１の部材５０の貫通穴５７を介して内側ウェブ５５を挟持する外側ウェブ３２を備える。詳しくは、外側ウェブ３２は、第１フランジ３２ａと、貫通部３２ｂと、第２フランジ３２ｃと、を有している。第１フランジは、外周側に歯部３１が形成されている環状のリム３１ｒから回転支持部５１の回転軸に向かって内径方向に広がっている部分である。貫通部３２ｂは、第１フランジ３２ａ内周端から回転軸方向に延びて貫通穴５７を貫通し、第２フランジ３２ｃに接続している。第２フランジ３２ｃは、貫通部３２ｂから貫通穴５７の外周縁部５７ｂよりも外周側に広がっている。このように、第２の部材３０の外側ウェブ３２は、回転軸方向において第１フランジ３２ａと第２フランジ３２ｃとの間に内側ウェブ５５の外周縁部５７ｂを挟持するように形成されている。言い換えると、第２の部材３０に設けられた第１フランジ３２ａ及び第２フランジ３２ｃは、第１の部材５０の一部を軸方向の両側から挟持する挟持部として機能する。 In this embodiment, the two side edges 58, 58 that define the through hole 57 face each other in the circumferential direction and are substantially parallel to the radial direction b1 (diameter direction) with respect to the gear rotation center. The second member 30 includes an outer web 32 that clamps the inner web 55 through the through hole 57 of the first member 50. In detail, the outer web 32 has a first flange 32a, a through portion 32b, and a second flange 32c. The first flange is a portion that spreads inwardly from the annular rim 31r on which the teeth portion 31 is formed on the outer periphery toward the rotation axis of the rotation support portion 51. The through portion 32b extends in the rotation axis direction from the inner peripheral end of the first flange 32a, passes through the through hole 57, and is connected to the second flange 32c. The second flange 32c spreads outwardly from the through portion 32b beyond the outer peripheral edge portion 57b of the through hole 57. In this way, the outer web 32 of the second member 30 is formed to sandwich the outer peripheral edge portion 57b of the inner web 55 between the first flange 32a and the second flange 32c in the rotation axis direction. In other words, the first flange 32a and the second flange 32c provided on the second member 30 function as a sandwiching portion that sandwiches a portion of the first member 50 from both sides in the axial direction.

第２の部材３０は、例えば成形済みの第１の部材５０に対して２色成形を行うことにより、第１の部材５０と一体化した状態で形成される。その際、第２の部材３０は、貫通穴５７に関しては貫通穴５７の内周側に空間を残して第１の部材５０の内側ウェブ５５を貫通し、内側ウェブ５５を表裏から挟持するよう形成される。また、第２の部材３０が成形される時、第１の部材５０の内側ウェブ５５の最外周面５５ａの外側には、第２の部材３０のリム３１ｒの内周面３１ｒａとが接触しない空間が形成されるよう２色成形を行う。 The second member 30 is formed in a state where it is integrated with the first member 50, for example, by performing two-color molding on the molded first member 50. In this case, the second member 30 is formed so as to penetrate the inner web 55 of the first member 50, leaving a space on the inner periphery side of the through hole 57, and to sandwich the inner web 55 from the front and back. In addition, when the second member 30 is molded, two-color molding is performed so that a space is formed outside the outermost peripheral surface 55a of the inner web 55 of the first member 50, which does not come into contact with the inner peripheral surface 31ra of the rim 31r of the second member 30.

即ち、本実施形態では、図３（ｃ）に示すように、上記の２つの個所において、第１の部材５０の外径側の部位と、第２の部材３０の内径側の部位は接触せず、空間ａ１、ａ２が形成される。空間ａ１は、径方向に所定の距離を空けて互いに対向している、第１の部材５０の貫通穴５７の内周縁部５７ａと第２の部材３０の貫通部３１ｂとの間の空間である。空間ａ２は、径方向に所定の距離を空けて互いに対向している、第１の部材５０の最外周面５５ａと第２の部材３０のリム３１ｒの内周面３１ｒａとの間の空間である。第１の部材５０はポリアセタール、ポリブチレンテレフタレート、ポリフェニレンスルフィド、ポリアミド、ナイロンなどの比較的、高剛性な合成樹脂材料（第１の樹脂材料）を用いて製作される。第２の部材３０は、第１の樹脂材料とは異なる第２の樹脂材料を用いて製作され、例えばポリアセタール樹脂（コポリマー）等の比較的摺動性の高い樹脂材料を用いることができる。 That is, in this embodiment, as shown in FIG. 3(c), the outer diameter side portion of the first member 50 and the inner diameter side portion of the second member 30 do not contact each other at the above two points, and spaces a1 and a2 are formed. The space a1 is the space between the inner peripheral edge portion 57a of the through hole 57 of the first member 50 and the through portion 31b of the second member 30, which face each other at a predetermined distance in the radial direction. The space a2 is the space between the outermost peripheral surface 55a of the first member 50 and the inner peripheral surface 31ra of the rim 31r of the second member 30, which face each other at a predetermined distance in the radial direction. The first member 50 is manufactured using a relatively high-rigidity synthetic resin material (first resin material) such as polyacetal, polybutylene terephthalate, polyphenylene sulfide, polyamide, and nylon. The second member 30 is made of a second resin material that is different from the first resin material, and can be a resin material with relatively high slidability, such as polyacetal resin (copolymer).

図４（ａ）、（ｂ）は、本実施形態において複合歯車１０を形成する成形型の一例を示している。金型１はＤＳＩ（Ｄｉｅ Ｓｌｉｄｅ Ｉｎｊｅｃｔｉｏｎ）のような手法により、第１の部材５０および第２の部材３０を射出成形し複合歯車１０を形成するために用いられる。この例では、金型１は固定側（ゲート側）の金型２と、移動駒４を有した可動側（反ゲート側）金型３とから成る。移動駒４は第１の部材５０が成形された後、第１の部材５０と共に第２の部材３０を成形する位置に金型内で移動することができる。 Figures 4(a) and (b) show an example of a molding die for forming the compound gear 10 in this embodiment. The die 1 is used to injection mold the first member 50 and the second member 30 to form the compound gear 10 by a method such as DSI (Die Slide Injection). In this example, the die 1 is composed of a fixed side (gate side) die 2 and a movable side (opposite gate side) die 3 having a moving piece 4. After the first member 50 has been molded, the moving piece 4 can be moved within the die to a position for molding the second member 30 together with the first member 50.

移動金型としての移動駒４は固定側の金型２の左半部（第１の固定金型）とともに第１の部材５０を成形する第１の成形部を構成し、移動駒４は固定側の金型２の右半部（第２の固定金型）とともに第２の部材３０を成形する第２の成形部を構成する。 The movable piece 4 as a movable mold constitutes a first molding section that molds the first member 50 together with the left half of the fixed mold 2 (first fixed mold), and the movable piece 4 constitutes a second molding section that molds the second member 30 together with the right half of the fixed mold 2 (second fixed mold).

図４（ａ）は、金型１において移動駒４が第１の部材５０を成形する位置にあり、第１の部材５０が成形する状態を示している。図４（ｂ）は移動駒４が第２の部材３０を成形する位置に移動しており、この位置で第２の部材３０が成形する状態を表した図である。 Figure 4(a) shows the state in which the moving piece 4 in the mold 1 is in a position to mold the first member 50, and the first member 50 is being molded. Figure 4(b) shows the state in which the moving piece 4 has moved to a position to mold the second member 30, and the second member 30 is being molded in this position.

即ち、この金型は、第１の部材を成形する第１の成形部と、第２の部材を成形する第２の成形部と、が単一の金型内に配置された構成である。そして、金型の可動側に設置された第１の成形部は、第１の部材の成形後に第１の部材と共に第２の成形部に対向する位置に移動し、第１の部材と第２の部材とが一体化するように第２の部材を成形する。 In other words, this mold has a configuration in which a first molding section that molds a first member and a second molding section that molds a second member are arranged within a single mold. Then, the first molding section, which is installed on the movable side of the mold, moves together with the first member to a position facing the second molding section after molding the first member, and molds the second member so that the first member and the second member are integrated.

図１（ａ）～図３（ｃ）に示すような本実施形態と、図１４（ａ）～図１５（ｃ）に示す従来例と比較すると、第１の部材にある内側ウェブと第２の部材にある外側ウェブの構成が異なっている。前述のように、複合歯車の第１の部材と第２の部材は強固に結合していることが好ましく、内側ウェブと外側ウェブとは挟持によって結合されている必要がある。 Comparing this embodiment shown in Figures 1(a) to 3(c) with the conventional example shown in Figures 14(a) to 15(c), the configuration of the inner web on the first member and the outer web on the second member is different. As mentioned above, it is preferable that the first member and the second member of the compound gear are firmly connected, and the inner web and the outer web must be connected by clamping.

また、歯車の駆動トルクで回転方向に位相ずれしないよう、第１の部材にアンカー形状を設け、第２の部材との接合強度を確保する必要がある。本実施形態と従来例はウェブの構成に大きな違いはあるものの、内側ウェブが外側ウェブに挟持されている点は共通である。また、アンカーとなる形状においては従来例では凹凸部６７が、本実施形態では貫通穴５７がその役割を果たしている。 In addition, to prevent phase shift in the rotational direction due to the driving torque of the gears, it is necessary to provide an anchor shape on the first member and ensure the joining strength with the second member. Although there is a significant difference between the web configuration in this embodiment and the conventional example, they have in common the fact that the inner web is sandwiched between the outer web. In addition, the role of the anchor shape is played by the uneven portion 67 in the conventional example, while in this embodiment, this role is played by the through hole 57.

しかしながら、本実施形態の複合歯車１０では、貫通穴５７の部位、および第１の部材５０の最外周の部位において、第１の部材５０の外径側と第２の部材３０の内径側が接触せずに空間（ａ１、ａ２）を形成している点で、従来例と大きく異なる。前述のように、図１３（ａ）～図１５（ｃ）のような従来構成において、第１の部材を第２の部材で覆うように構成し、上記のような空間を有していない複合歯車は経年収縮の違いから歪が生じ、破損する懸念があった。あるいは、経年収縮を考慮しても破損の可能性が十分小さい耐用期間を設定したり、コスト増加を許容して破損が生じないような第１の部材５０および第２の部材３０の肉厚を設定したりする等の対策が必要となっていた。 However, the compound gear 10 of this embodiment is significantly different from the conventional example in that the outer diameter side of the first member 50 and the inner diameter side of the second member 30 do not come into contact with each other at the through hole 57 and the outermost periphery of the first member 50, forming spaces (a1, a2). As mentioned above, in the conventional configurations such as those shown in Figures 13(a) to 15(c), the first member is covered by the second member, and there is a concern that a compound gear without the above-mentioned space may be distorted and damaged due to differences in aging shrinkage. Alternatively, measures such as setting a service life that is sufficiently small to cause damage even when aging shrinkage is taken into account, or setting the thickness of the first member 50 and the second member 30 so that damage will not occur, even if an increase in cost is allowed, were necessary.

これに対して、図１（ａ）～３（ｃ）で示す本実施形態では、第１の部材５０と第２の部材３０の間に空間ａ１、ａ２が形成されており、第１の部材５０が第２の部材３０の収縮を阻害しにくくなり、歪の発生が抑制される。 In contrast, in the present embodiment shown in Figures 1(a) to 3(c), spaces a1 and a2 are formed between the first member 50 and the second member 30, making it difficult for the first member 50 to inhibit the contraction of the second member 30, and suppressing the occurrence of distortion.

例えば、図５（ａ）～図６（ｃ）は、本実施形態の複合歯車１０において第２の部材３０が収縮した状態を示している。第２の部材３０は円形の成形品であるから、内径方向の収縮は円中心に向かって発生する。そのため収縮前に存在していた空間ａ１、ａ２は、より小さな空間ａ３、ａ４へと縮小し、新たに空間ａ５が形成されている。つまり、第２の部材３０の収縮に伴い、内側ウェブ５５の貫通穴５７の内周縁部５７ａと外側ウェブ３２の貫通部３２ｂとの間の径方向の距離、及び、第１の部材５０の最外周面５５ａと第２の部材３０のリム３１ｒの内周面３１ｒａとの間の距離が縮まる。その一方で、内側ウェブ５５の貫通穴５７の外周縁部５７ｂと外側ウェブ３２の貫通部３２ｂとの間に径方向に隙間（空間ａ５）が生じる。このように、第１の部材５０と第２の部材３０の間の空間ａ１～ａ５は、第１の部材５０と第２の部材３０の収縮率の差によって生じる、径方向に関する内側ウェブ５５と外側ウェブ３２の相対的な位置変化を吸収する受け代として機能する。この受け代の作用により、複合歯車の歪の発生を抑制することができる。 For example, Figures 5(a) to 6(c) show the state in which the second member 30 is contracted in the compound gear 10 of this embodiment. Since the second member 30 is a circular molded product, the contraction in the inner diameter direction occurs toward the center of the circle. Therefore, the spaces a1 and a2 that existed before the contraction are reduced to smaller spaces a3 and a4, and a new space a5 is formed. In other words, as the second member 30 contracts, the radial distance between the inner peripheral edge 57a of the through hole 57 of the inner web 55 and the through portion 32b of the outer web 32, and the distance between the outermost peripheral surface 55a of the first member 50 and the inner peripheral surface 31ra of the rim 31r of the second member 30 are reduced. On the other hand, a radial gap (space a5) is generated between the outer peripheral edge 57b of the through hole 57 of the inner web 55 and the through portion 32b of the outer web 32. In this way, the spaces a1 to a5 between the first member 50 and the second member 30 function as support spaces that absorb the relative positional changes in the radial direction between the inner web 55 and the outer web 32 that occur due to the difference in the shrinkage rates of the first member 50 and the second member 30. This support space function can suppress the occurrence of distortion in the compound gear.

また、本実施形態の複合歯車１０の第１の部材５０の貫通穴５７は、放射方向ｂ１と同じ向きの２つの側縁部５８、５８を備える。前述のように、第２の部材３０は径方向の収縮とほぼ同じ比率で周方向にも収縮する。そのため、第２の部材３０は第１の部材５０の貫通穴５７の側縁部５８、５８に接した状態で収縮する。この作用により、第２の部材３０に収縮が生じても、歯車の第１の部材５０と第２の部材３０の間は、周方向において間に隙間が生じることがなく、両者の密な結合状態が維持される。さらに、第２の部材３０の収縮は放射方向にほぼ一致する方向を持つ貫通穴５７の側縁部５８、５８に沿って生じるので、歯車の周方向に関しても歪が生じることを低減する。 In addition, the through hole 57 of the first member 50 of the compound gear 10 of this embodiment has two side edges 58, 58 oriented in the same direction as the radial direction b1. As described above, the second member 30 also shrinks in the circumferential direction at approximately the same rate as the radial shrinkage. Therefore, the second member 30 shrinks while in contact with the side edges 58, 58 of the through hole 57 of the first member 50. Due to this action, even if the second member 30 shrinks, no gap is generated between the first member 50 and the second member 30 of the gear in the circumferential direction, and the close connection between the two is maintained. Furthermore, since the shrinkage of the second member 30 occurs along the side edges 58, 58 of the through hole 57, which have a direction that is approximately the same as the radial direction, distortion in the circumferential direction of the gear is also reduced.

以上のように、内側ウェブ５５と外側ウェブ３２の相対的な位置変化が生じた後も、径方向において内側ウェブ５５が外側ウェブ３２に挟持され、かつ、貫通穴５７を介して外側ウェブ３２が内側ウェブ５５に係合された状態は維持される。つまり、上記の空間ａ１～ａ５は、第１の部材５０及び第２の部材３０を軸方向及び周方向に関して相対移動不能に結合することに影響を与えることなく、収縮率の差による第１の部材５０及び第２の部材３０の寸法変化を許容して歪の発生を抑制可能とする。言い換えると、本実施形態の複合歯車は、第１の部材５０と第２の部材３０を強固に結合させつつ、しかも経時収縮による割れのような破損を抑制することができる。以下では、図７（ａ）～図１２（ｂ）を参照して、本実施形態の複合歯車の細部を変形した構成につき説明する。 As described above, even after the relative positional change occurs between the inner web 55 and the outer web 32, the inner web 55 is held by the outer web 32 in the radial direction, and the outer web 32 is engaged with the inner web 55 through the through hole 57. In other words, the above spaces a1 to a5 allow the first member 50 and the second member 30 to change in size due to the difference in shrinkage rate, without affecting the connection of the first member 50 and the second member 30 so that they cannot move relative to each other in the axial and circumferential directions, and make it possible to suppress the occurrence of distortion. In other words, the compound gear of this embodiment can firmly connect the first member 50 and the second member 30, while suppressing damage such as cracks due to shrinkage over time. Below, with reference to Figures 7(a) to 12(b), a detailed modified configuration of the compound gear of this embodiment will be described.

図７（ａ）～図１２（ｂ）は、本実施形態の複合歯車の細部を変形した構成を示している。以下では、図１（ａ）～４（ｂ）に示した複合歯車１０および金型１と同一の構成には同一符号を付し、重複する説明は省略するものとする。 Figures 7(a) to 12(b) show configurations in which the details of the compound gear of this embodiment have been modified. In the following, the same components as those of the compound gear 10 and die 1 shown in Figures 1(a) to 4(b) are given the same reference numerals, and duplicated explanations will be omitted.

図３（ｃ）に示した構成では、貫通穴５７の側縁部５８、５８が回転軸を中心とする放射方向ｂ１に一致している。これに対して、図７（ａ）～（ｃ）に示した複合歯車１１は、貫通穴５７の側縁部ｂ２、側縁部ｂ３は、放射方向ｂ１に対して傾斜した角度を有する。図７（ａ）は複合歯車１１の図３（ｂ）の複合歯車１０と同じ位置における断面を示している。図７（ｂ）は放射方向ｂ１よりも小さい角度で側縁部ｂ２、ｂ２を形成した例を、図７（ｃ）は放射方向ｂ１よりも大きい角度で側縁部ｂ３、ｂ３を形成した例を示している。ただし、側縁部の傾斜角度の大小は、貫通穴５７の中心角φ０（図７（ａ））を基準（０°）として、２つの側縁部の稜線を延長した線がなす角φ１、φ２が大きいか小さいかによって表す。側縁部の傾斜角度が負の場合、図７（ｂ）のように、内径方向に向かうときの側縁部ｂ２、ｂ２の周方向の間隔の減少率が、側縁部を放射方向ｂ１、ｂ１に沿って形成した場合よりも小さい（側縁部ｂ２、ｂ２がより平行に近い）構成となる。また、側縁部の傾斜角度が正の場合、図７（ｃ）のように、内径方向に向かうときの側縁部ｂ３、ｂ３の周方向の間隔の減少率が、側縁部を放射方向ｂ１、ｂ１に沿って形成した場合よりも大きい構成となる。言い換えれば、側縁部の傾斜角度が正の場合側縁部の延長線の交点が、複合歯車１０の回転軸よりも貫通穴５７に近い構成となる。 In the configuration shown in FIG. 3(c), the side edges 58, 58 of the through hole 57 coincide with the radial direction b1 centered on the rotation axis. In contrast, in the compound gear 11 shown in FIG. 7(a) to (c), the side edges b2, b3 of the through hole 57 have an angle inclined with respect to the radial direction b1. FIG. 7(a) shows a cross section of the compound gear 11 at the same position as the compound gear 10 in FIG. 3(b). FIG. 7(b) shows an example in which the side edges b2, b2 are formed at an angle smaller than the radial direction b1, and FIG. 7(c) shows an example in which the side edges b3, b3 are formed at an angle larger than the radial direction b1. However, the size of the inclination angle of the side edges is expressed by whether the angles φ1, φ2 formed by the lines extending the ridgelines of the two side edges are large or small, with the central angle φ0 (FIG. 7(a)) of the through hole 57 as the reference (0°). When the inclination angle of the side edge is negative, as shown in FIG. 7(b), the rate of decrease in the circumferential spacing of the side edge b2, b2 when moving in the inward direction is smaller than when the side edge is formed along the radial direction b1, b1 (the side edge b2, b2 is closer to parallel). When the inclination angle of the side edge is positive, as shown in FIG. 7(c), the rate of decrease in the circumferential spacing of the side edge b3, b3 when moving in the inward direction is larger than when the side edge is formed along the radial direction b1, b1. In other words, when the inclination angle of the side edge is positive, the intersection of the extension lines of the side edge is closer to the through hole 57 than to the rotation axis of the compound gear 10.

このような構成の複合歯車１１によると第２の部材３０の収縮に異方性があったとしても歪の抑制と結合力の維持が可能となる。例えば、第２の部材３０の周方向の収縮率より、径方向の収縮率のほうが大きいと、図３（ａ）～（ｃ）のような構成では、第１の部材５０の貫通穴５７の２つの側縁部５８が第２の部材３０の収縮の抵抗となって引張応力が生じる可能性がある。このような第２の部材３０の収縮の異方性に対しては、図７（ｂ）のように貫通穴５７の２つの側縁部ｂ２、ｂ２の交角φ１を小さくにすることで第２の部材３０の収縮が阻害されにくくなり、複合歯車１１の歪の発生を軽減することができる。 With a compound gear 11 of this configuration, it is possible to suppress distortion and maintain the binding force even if the shrinkage of the second member 30 is anisotropic. For example, if the shrinkage rate of the second member 30 is greater in the radial direction than in the circumferential direction, in a configuration such as that shown in Figures 3(a) to (c), the two side edges 58 of the through hole 57 of the first member 50 may resist the shrinkage of the second member 30, causing tensile stress. To deal with the anisotropy of the shrinkage of the second member 30, the intersection angle φ1 of the two side edges b2, b2 of the through hole 57 can be made small as shown in Figure 7(b), making it difficult for the shrinkage of the second member 30 to be hindered, and the occurrence of distortion in the compound gear 11 can be reduced.

また、第２の部材３０の径方向の収縮率より周方向の収縮率が大きい場合には周方向において第１と第２の部材間に隙間が生じることになる。この場合には、第１の部材５０と第２の部材３０の間にガタを生じる可能性がある。このような第２の部材３０の収縮の異方性に対しては、図７（ｃ）のように貫通穴の２つの側縁部ｂ３、ｂ３の交角φ２を大きくとすることで、第２の部材が収縮しても隙間が生じず第１の部材５０と第２の部材３０の結合が密に維持される。 In addition, if the circumferential shrinkage rate of the second member 30 is greater than the radial shrinkage rate, a gap will be generated between the first and second members in the circumferential direction. In this case, there is a possibility that a rattle will be generated between the first member 50 and the second member 30. To deal with this anisotropy of shrinkage of the second member 30, the intersection angle φ2 of the two side edges b3, b3 of the through hole is made large as shown in FIG. 7(c), so that no gap will be generated even if the second member shrinks, and the bond between the first member 50 and the second member 30 will be maintained tight.

上記の例から明らかなように、第１の部材５０の貫通穴の２つの側縁部の交角は、第２の部材３０の収縮率、例えばその異方性に応じて決定しておけばよい。その場合、直線状の側縁部の角度は、例えば、前記回転軸部の直径方向（放射方向）に対して－１０°から＋１０°の範囲の傾斜角度となるよう選ぶことができる。 As is clear from the above example, the intersection angle of the two side edges of the through hole of the first member 50 may be determined in advance according to the shrinkage rate of the second member 30, for example, its anisotropy. In this case, the angle of the linear side edges can be selected to be an inclination angle in the range of -10° to +10° with respect to the diameter direction (radial direction) of the rotating shaft portion, for example.

図８（ａ）～（ｃ）は複合歯車１２の異なる構成を示している。ここで、図８（ａ）は複合歯車１２の正面図、図８（ｂ）は断面図、図８（ｃ）は詳細図である。この例は、第２の部材３０の肉厚方向の収縮を考慮した構成である。即ち、ポリアセタール樹脂などから成る第２の部材３０の収縮は内径方向、周方向だけでなく肉厚方向にも僅かながら発生する。この肉厚方向の収縮は外径や円周に比べ非常に小さいため、生じる歪は小さく、成形品が割れる可能性は低い。しかしながら、本実施形態は、第２の部材３０によって第１の部材５０が挟持される構成であるから、わずかな肉厚方向の収縮でも第２の部材の内径方向への収縮を阻害する可能性がある。そこで、図８（ｂ）、（ｃ）に示すように、複合歯車１２には、第１の部材５０の内側ウェブ５５は内側に向かって減肉、即ち厚みが漸減するような勾配ｃを設けている。このように第１の部材５０の内側ウェブ５５に厚みの勾配ｃを設けた構成により、第２の部材３０が肉厚方向に収縮しても内径方向への収縮が阻害されにくくなり、上述の作用が得られやすくなる。言い換えると、外側ウェブ３２の貫通部３２ｂ等の収縮により、内側ウェブ５５を挟持している第１フランジ３２ａと第２フランジ３２ｃとが軸方向に接近しようとする。このとき、内側ウェブ５５が有する勾配ｃによって外側ウェブ３２が内径方向の反力を内側ウェブ５５から受けることで、第２の部材３０が内径方向に均一に収縮しやすくなる。なお、勾配ｃは、内側ウェブ５５のうち少なくとも第２の部材３０に挟持される部分に、設定されているものとする。 Figures 8(a) to (c) show different configurations of the compound gear 12. Here, Figure 8(a) is a front view of the compound gear 12, Figure 8(b) is a cross-sectional view, and Figure 8(c) is a detailed view. This example is a configuration that takes into consideration the shrinkage in the thickness direction of the second member 30. That is, the shrinkage of the second member 30 made of polyacetal resin or the like occurs not only in the inner diameter direction and circumferential direction but also slightly in the thickness direction. Since this shrinkage in the thickness direction is very small compared to the outer diameter and circumference, the distortion that occurs is small and the possibility of the molded product cracking is low. However, since this embodiment is configured so that the first member 50 is clamped by the second member 30, even a slight shrinkage in the thickness direction may hinder the shrinkage of the second member in the inner diameter direction. Therefore, as shown in Figures 8(b) and (c), the compound gear 12 has a gradient c in which the inner web 55 of the first member 50 is gradually reduced in thickness toward the inside. In this way, by providing the inner web 55 of the first member 50 with a thickness gradient c, even if the second member 30 shrinks in the thickness direction, the shrinkage in the inner diameter direction is not hindered, and the above-mentioned effect is easily obtained. In other words, the first flange 32a and the second flange 32c, which sandwich the inner web 55, try to approach each other in the axial direction due to the shrinkage of the through-hole 32b of the outer web 32. At this time, the outer web 32 receives a reaction force in the inner diameter direction from the inner web 55 due to the gradient c of the inner web 55, so that the second member 30 tends to shrink uniformly in the inner diameter direction. Note that the gradient c is set at least in the part of the inner web 55 that is sandwiched by the second member 30.

図９（ａ）～（ｃ）は複合歯車１３の異なる構成を示している。ここで、図９（ａ）は複合歯車１３の正面図、（ｂ）は背面図、（ｃ）は断面図である。この複合歯車１３は、軸方向視で第１の部材５０の貫通穴５７上の位置（図示の例では黒点で表した４点）に、第２の部材３０を射出する時のゲート痕３３を有する。ゲートが複数ある場合、ゲート痕３３の少なくとも一部（好ましくは全て）が貫通穴５７上にあればよい。また、各ゲートについて、ゲート痕３３の面積の少なくとも一部（好ましくは全て）が軸方向視で貫通穴５７と重なっていればよい。このような第２の部材３０をインサート成形する際のゲートの配置をゲート痕３３で示した位置にとることにより、第２の部材３０を射出成形する際に生じる圧力を、貫通穴を通じてゲートの反対側へ逃がすことができる。これにより、第１の部材５０が変形しにくくなる利点がある。 9(a) to (c) show different configurations of the compound gear 13. Here, FIG. 9(a) is a front view of the compound gear 13, (b) is a rear view, and (c) is a cross-sectional view. This compound gear 13 has a gate mark 33 when the second member 30 is injected at a position on the through hole 57 of the first member 50 when viewed in the axial direction (four points indicated by black dots in the illustrated example). When there are multiple gates, it is sufficient that at least a part (preferably all) of the gate mark 33 is on the through hole 57. Also, for each gate, it is sufficient that at least a part (preferably all) of the area of the gate mark 33 overlaps with the through hole 57 when viewed in the axial direction. By arranging the gate at the position indicated by the gate mark 33 when insert molding such a second member 30, the pressure generated when injection molding the second member 30 can be released to the opposite side of the gate through the through hole. This has the advantage that the first member 50 is less likely to deform.

図１０（ａ）、（ｂ）は複合歯車１４の異なる構成を示している。ここで、図１０（ａ）は複合歯車１４の正面図、（ｂ）は貫通穴５７付近の詳細図である。この複合歯車１４は、第１の部材５０の貫通穴５７の隅部Ｒ（corner part）に面取り、または円筒面のような曲線形状を有する。貫通穴５７は、前述同様に２つの側縁部５８、５８と、これらを繋ぐ外周縁部５７ｂおよび内周縁部５７ａにより画成された扇面形状である。即ち、前記側縁部５８，５８と、外周縁部５７ｂおよび／または前記内周縁部５７ａと、を面取り、または円筒面のような曲線形状を有する隅部Ｒを介して連続させる。 Figures 10(a) and (b) show different configurations of the compound gear 14. Here, Figure 10(a) is a front view of the compound gear 14, and (b) is a detailed view of the vicinity of the through hole 57. This compound gear 14 has a corner part R of the through hole 57 of the first member 50 that is chamfered or has a curved shape like a cylindrical surface. As described above, the through hole 57 has a sector shape defined by two side edges 58, 58 and an outer peripheral edge 57b and an inner peripheral edge 57a that connect them. In other words, the side edges 58, 58 are connected to the outer peripheral edge 57b and/or the inner peripheral edge 57a via a corner R that is chamfered or has a curved shape like a cylindrical surface.

特に、図１０（ａ）、（ｂ）に示すように内周縁部５７ａと側縁部５８、５８との間の隅部Ｒに面取り、または円筒面を設けることができる。このように内周縁部５７ａと側縁部５８、５８との間の隅部Ｒに面取りや円筒面を設けず、角部（sharp edged corner）とする構成では、歯車の駆動トルクによって隅部にはノッチ効果と呼ばれる応力集中が発生する。この応力は、隅部の角部を引き裂くように働く。しかしながら、上記のようにこのような構成にすることで隅部への応力が分散し、複合歯車１４の機械的強度を高めることができる。 In particular, as shown in Figures 10(a) and (b), the corners R between the inner peripheral edge 57a and the side edges 58, 58 can be chamfered or provided with a cylindrical surface. In this configuration where the corners R between the inner peripheral edge 57a and the side edges 58, 58 are not chamfered or provided with a cylindrical surface, but are instead sharp edged corners, the driving torque of the gear generates a stress concentration called the notch effect at the corners. This stress acts to tear the corners apart. However, by using such a configuration as described above, the stress at the corners can be dispersed, and the mechanical strength of the compound gear 14 can be increased.

図１１（ａ）～（ｃ）、および図１２（ａ）、（ｂ）は、それぞれさらに異なる構成を有する複合歯車１５、およびこの複合歯車１５の製造に用いられる成形型としての金型１を示している。ここで、図１１（ａ）は複合歯車１５の正面図、（ｂ）は断面図、（ｃ）は詳細図である。図１２（ａ）は金型１の断面図であり、金型１の構成は図４で表したものと同等である。また、図１２（ｂ）は第２の部材３０が成形される際の状態を示している。図１１（ａ）～（ｃ）の複合歯車１５では、成形済みの第１の部材５０の内側ウェブ５５の最外周部にリング状の突条ｄを設けてある。このような構成では、成形済みの第１の部材５０に対して第２の部材３０を２色成形する際、第１の部材５０の突条ｄと金型駒５を接触させることにより、第２の部材３０と第１の部材５０との間に第２の部材３０用の樹脂材料が充填されるのを抑制できる。即ち、第１の部材５０の最外周と第２の部材３０の内周の間に、確実に両者が接触せず、第２の部材３０の収縮を吸収する空間を形成することができる。そのため、本実施形態の構造を備えた複合歯車を容易かつ確実に製造することができる。 Figures 11(a)-(c) and 12(a)-(b) show compound gears 15 with different configurations, and a mold 1 as a molding die used to manufacture the compound gears 15. Here, Figure 11(a) is a front view of the compound gear 15, (b) is a cross-sectional view, and (c) is a detailed view. Figure 12(a) is a cross-sectional view of the mold 1, and the configuration of the mold 1 is the same as that shown in Figure 4. Also, Figure 12(b) shows the state when the second member 30 is molded. In the compound gear 15 of Figures 11(a)-(c), a ring-shaped protrusion d is provided on the outermost periphery of the inner web 55 of the molded first member 50. In this configuration, when the second member 30 is molded in two colors for the molded first member 50, the protrusion d of the first member 50 is brought into contact with the mold piece 5, so that the resin material for the second member 30 can be prevented from filling between the second member 30 and the first member 50. In other words, a space can be formed between the outermost circumference of the first member 50 and the inner circumference of the second member 30 so that they do not come into contact with each other and can absorb the shrinkage of the second member 30. Therefore, a compound gear having the structure of this embodiment can be easily and reliably manufactured.

また、図２０（ａ、ｂ）にはさらに異なる構成を示している。この構成は、図３（ａ～ｃ）に示す構成と比べて、内側ウェブ５５に形成される各貫通穴５７の、第１の部材５０の回転中心に対する中心角φが異なっている。言い換えると、図２０（ａ、ｂ）の構成と図３（ａ～ｃ）の構成とで、周方向に関して貫通穴５７が空けられている領域と内側ウェブ５５の一部として樹脂が充填されている領域との比率が異なっている。この図のように第１の部材５０の貫通穴５７の中心角φを制御することで、第２の部材３０を成形する際に生じる圧力を調整できると同時に、第１の部材５０の内側ウェブ５５の剛性を調整することができる。これにより、第２の部材３０の収縮による歪の発生を抑制する作用を維持しながら、第２の部材３０の成形による第１の部材５０の内側ウェブ５５の変形を抑制する作用を得ることができる。 20(a,b) shows a further different configuration. In this configuration, the central angle φ of each through hole 57 formed in the inner web 55 with respect to the center of rotation of the first member 50 is different from that shown in FIG. 3(a-c). In other words, the ratio of the area in which the through holes 57 are formed in the circumferential direction to the area in which the resin is filled as part of the inner web 55 is different between the configurations shown in FIG. 20(a,b) and FIG. 3(a-c). By controlling the central angle φ of the through holes 57 of the first member 50 as shown in this figure, the pressure generated when the second member 30 is molded can be adjusted, and at the same time, the rigidity of the inner web 55 of the first member 50 can be adjusted. This makes it possible to obtain the effect of suppressing the deformation of the inner web 55 of the first member 50 due to the molding of the second member 30 while maintaining the effect of suppressing the occurrence of distortion due to shrinkage of the second member 30.

上記を鑑みて、貫通穴５７の２つの側縁部の稜線を延長した線がなす角（中心角φ）は、例えば以下の範囲であると好適である。

Figure 0007483505000001
ただし、l[mm]は第１の部材５０の最外周面から貫通穴５７の外周縁部５７ｂまでの長さ、t[mm]は第１の部材５０の内側ウェブ５５の厚み（貫通穴５７の付近における厚み）を示す。また、 In consideration of the above, it is preferable that the angle (central angle φ) formed by the lines extending from the ridge lines of the two side edges of the through hole 57 is within the following range, for example.
Figure 0007483505000001
 Here, l [mm] is the length from the outermost surface of the first member 50 to the outer peripheral edge 57b of the through hole 57, and t [mm] is the thickness of the inner web 55 of the first member 50 (the thickness in the vicinity of the through hole 57).

本実施形態における上記の各構成例では、図１（ａ）～図３（ｃ）に示すように、第１の部材５０に貫通穴５７が設けられている例を示した。しかし、これに限るものではない。図２１（ａ～ｃ）、図２２（ａ～ｃ）、図２３（ａ～ｅ）は、本実施形態の複合歯車の細部を変形した構成を示している。以下では、図１（ａ）～３（ｃ）に示した複合歯車１０と同一の構成には同一符号を付し、重複する説明は省略するものとする。 In the above configuration examples of this embodiment, as shown in Figures 1(a) to 3(c), a through hole 57 is provided in the first member 50. However, this is not limited to this. Figures 21(a) to 21(c), 22(a) to 22(c), and 23(a) to 23(e) show configurations in which the details of the compound gear of this embodiment are modified. In the following, the same components as those of the compound gear 10 shown in Figures 1(a) to 3(c) are given the same reference numerals, and duplicated explanations will be omitted.

図２１（ａ）は、一変形例の正面図を示し、（ｂ）は（ａ）に示す複合歯車のＥ－Ｅ部分における断面図を示し、（ｃ）はその詳細図を示している。ここに示すように、第２の部材３０に貫通穴５７が設けられていてもよい。この場合、第１の部材５０の内側ウェブ５５に、径方向に広がる第１フランジ５５ｃと、軸方向に延びて貫通穴５７を通る貫通部５５ｄと、外側ウェブ３２の第１フランジ５５ｃとは反対側で径方向に広がる第２フランジ５５ｅと、を設ける。これにより、第１フランジ５５ｃ及び第２フランジ５５ｅによって外側ウェブ３２が軸方向の両側から挟持された状態で、第１の部材５０と第２の部材３０が結合される。言い換えると、第１の部材５０に設けられた第１フランジ５５ｃ及び第２フランジ５５ｅは、第２の部材３０の一部を軸方向の両側から挟持する挟持部として機能する。つまり、本変形例では、第１の部材５０の一部が径方向の両側から第２の部材３０の一部を挟持する構成となっている。 21(a) shows a front view of one modified example, (b) shows a cross-sectional view of the compound gear shown in (a) at part E-E, and (c) shows a detailed view thereof. As shown here, the second member 30 may be provided with a through hole 57. In this case, the inner web 55 of the first member 50 is provided with a first flange 55c extending in the radial direction, a through portion 55d extending in the axial direction and passing through the through hole 57, and a second flange 55e extending in the radial direction on the opposite side to the first flange 55c of the outer web 32. As a result, the first member 50 and the second member 30 are joined together in a state in which the outer web 32 is sandwiched by the first flange 55c and the second flange 55e from both sides in the axial direction. In other words, the first flange 55c and the second flange 55e provided on the first member 50 function as a sandwiching portion that sandwiches a part of the second member 30 from both sides in the axial direction. In other words, in this modified example, a portion of the first member 50 clamps a portion of the second member 30 from both radial sides.

本変形例においては、貫通穴５７の外周縁部５７ｂと貫通部５５ｂの外周側の面との間に径方向の空間ａ６を設けておく。また、内側ウェブ５５の最外周面と第２の部材３０のリム３１ｒとの間にも径方向の空間ａ７を設けておく。これらの空間ａ６，ａ７は、図１（ａ）～図３（ｃ）の構成における空間ａ１，ａ２と同様に、第１の部材と第２の部材の結合強度を維持しつつ、第１の部材と第２の部材の収縮率の差によって生じる相対的な位置変化を吸収する受け代として機能する。 In this modified example, a radial space a6 is provided between the outer peripheral edge 57b of the through hole 57 and the outer peripheral surface of the through portion 55b. A radial space a7 is also provided between the outermost peripheral surface of the inner web 55 and the rim 31r of the second member 30. These spaces a6 and a7 function as support spaces that absorb the relative positional changes caused by the difference in the shrinkage rates of the first and second members while maintaining the bonding strength between the first and second members, similar to the spaces a1 and a2 in the configurations of Figures 1(a) to 3(c).

本変形例では、２色形成を行う際に、第２の部材３０を形成した後に第１の部材５０を形成することができる。本変形例の構成により、第２の部材３０の材料の方が第１の部材５０の材料より融点が高い場合は、第２の部材３０に貫通穴５７を設けておいた方が歯車の性能を高めることができる。 In this modified example, when performing two-color formation, the first member 50 can be formed after the second member 30 is formed. With the configuration of this modified example, if the material of the second member 30 has a higher melting point than the material of the first member 50, the gear performance can be improved by providing a through hole 57 in the second member 30.

また図２２（ａ）は別の変形例の正面図を示し、（ｂ）は（ａ）に示す複合歯車のＦ－Ｆ部分の断面図を示し、（ｃ）はその詳細図である。このように、第１の部材５０に設けた断面が径方向内向きに開いたコの字状（squared-C shape）の係合形状５０Ａと、第２の部材３０に設けた断面が径方向外向きに開いたコの字状の係合形状３０Ａとが組み合わせられていてもよい。つまり、本変形例では、第１の部材５０の一部（５０Ａ）が軸方向の両側から第２の部材３０の一部を挟持する第１挟持部として機能すると同時に、第２の部材３０の一部（３０Ａ）が軸方向の両側から第１の部材５０の一部を挟持する第２挟持部として機能する。また、本変形例は、第１の部材又は第２の部材に設けた貫通穴を介さずに、第１の部材及び第２の部材の一方が他方を挟持する構成の一例である。 22(a) shows a front view of another modified example, (b) shows a cross-sectional view of the F-F portion of the compound gear shown in (a), and (c) shows a detailed view thereof. In this manner, a square-C shaped engagement shape 50A with a cross section provided on the first member 50 opening radially inward and a square-C shaped engagement shape 30A with a cross section provided on the second member 30 opening radially outward may be combined. That is, in this modified example, a part (50A) of the first member 50 functions as a first clamping part that clamps a part of the second member 30 from both sides in the axial direction, and at the same time, a part (30A) of the second member 30 functions as a second clamping part that clamps a part of the first member 50 from both sides in the axial direction. This modified example is also an example of a configuration in which one of the first member and the second member clamps the other without using a through hole provided in the first member or the second member.

本変形例において、第２の部材３０の最内周面である係合形状３０Ａの内周面と、径方向において係合形状３０Ａと対向する第１の部材５０の面（回転支持部５１の外径部５４）との間に空間ａ９が設けられている。また、第１の部材５０の係合形状５０Ａの最外周面と、径方向において係合形状５０Ａと対向する第２の部材３０のリム３１ｒとの間に空間ａ８が設けられている。これらの空間ａ８，ａ９は、図１（ａ）～図３（ｃ）の構成における空間ａ１，ａ２と同様に、第１の部材と第２の部材の結合強度を維持しつつ、第１の部材と第２の部材の収縮率の差によって生じる相対的な位置変化を吸収する受け代として機能する。これにより、成形品の厚みは増す可能性はあるが、成形品を製造するための型の加工を簡略化させることができる。 In this modified example, a space a9 is provided between the inner peripheral surface of the engagement shape 30A, which is the innermost peripheral surface of the second member 30, and the surface of the first member 50 (the outer diameter portion 54 of the rotation support portion 51) that faces the engagement shape 30A in the radial direction. Also, a space a8 is provided between the outermost peripheral surface of the engagement shape 50A of the first member 50 and the rim 31r of the second member 30 that faces the engagement shape 50A in the radial direction. These spaces a8 and a9, like the spaces a1 and a2 in the configurations of Figures 1(a) to 3(c), function as a support that absorbs relative positional changes caused by the difference in shrinkage rates between the first member and the second member while maintaining the bonding strength between the first member and the second member. This may increase the thickness of the molded product, but it is possible to simplify the processing of the mold for manufacturing the molded product.

さらに図２３（ａ）は別の変形例の第１の部材５０の斜視図であり、（ｂ）は第二の部材３０を含んだ複合歯車１０の斜視図である。（ｃ）は複合歯車１０の正面図を示し、（ｄ）および（ｆ）はそれぞれ複合歯車１０のＦ－Ｆ部分の断面図、Ｇ－Ｇ部分の断面図を示す。また（ｅ）および（ｇ）は（ｄ）（ｆ）それぞれの詳細図を示す。 Furthermore, Figure 23(a) is a perspective view of the first member 50 of another modified example, and (b) is a perspective view of the compound gear 10 including the second member 30. (c) shows a front view of the compound gear 10, and (d) and (f) show cross-sectional views of the F-F portion and the G-G portion of the compound gear 10, respectively. Also, (e) and (g) show detailed views of (d) and (f), respectively.

本変形例の第１の部材５０の内側ウェブ５５は、外周に複数の凹部５５ｕおよび複数の凸部５５ｐを有している。一方、第２の部材３０は、外側ウェブ３２の第１フランジ３２ａと第２フランジ３２ｃが内側ウェブ５５の凸部５５ｐを径方向の両側から挟み込むように形成されている。 The inner web 55 of the first member 50 in this modified example has multiple recesses 55u and multiple protrusions 55p on its outer periphery. On the other hand, the second member 30 is formed such that the first flange 32a and the second flange 32c of the outer web 32 sandwich the protrusions 55p of the inner web 55 from both radial sides.

本変形例において、第２の部材３０の最内周面である外側ウェブ３２の内周面と、径方向において外側ウェブ３２と対向する第１の部材５０の面（回転支持部５１の外径部５４）との間に空間ａ１０が設けられている。また、第１の部材５０の最外周面である凸部５５ｐの外周面と、径方向において凸部５５ｐと対向する第２の部材３０のリム３１ｒとの間に空間ａ１１が設けられている。さらに、凹部５５ｕの外周面と、径方向において凹部５５ｕと対向する第２の部材３０の面（第１フランジ３２ａ及び第２フランジ３２ｃを接続して軸方向に延びる面）との間にも、空間ａ１２が設けられている。これらの空間ａ１０～ａ１２は、図１（ａ）～図３（ｃ）の構成における空間ａ１，ａ２と同様に、第１の部材と第２の部材の結合強度を維持しつつ、第１の部材と第２の部材の収縮率の差によって生じる相対的な位置変化を吸収する受け代として機能する。 In this modified example, a space a10 is provided between the inner peripheral surface of the outer web 32, which is the innermost peripheral surface of the second member 30, and the surface of the first member 50 (the outer diameter portion 54 of the rotation support portion 51) that faces the outer web 32 in the radial direction. A space a11 is provided between the outer peripheral surface of the convex portion 55p, which is the outermost peripheral surface of the first member 50, and the rim 31r of the second member 30 that faces the convex portion 55p in the radial direction. Furthermore, a space a12 is also provided between the outer peripheral surface of the concave portion 55u and the surface of the second member 30 that faces the concave portion 55u in the radial direction (the surface that connects the first flange 32a and the second flange 32c and extends in the axial direction). These spaces a10 to a12 function as a support that absorbs the relative position change caused by the difference in the shrinkage rate between the first member and the second member while maintaining the bonding strength between the first member and the second member, similar to the spaces a1 and a2 in the configurations of Figures 1(a) to 3(c).

本変形例は、第１の部材又は第２の部材に設けた貫通穴を介さずに、第１の部材及び第２の部材の一方が他方を挟持する構成の他の一例である。これにより、成形品である複合歯車１０を製造するための型の加工を簡略化させることができる。なお、図２３（ａ）～（ｇ）は、第１の部材５０に凹部５５ｕおよび凸部５５ｐを備える例を示したが、第２の部材３０の内周に凹部および凸部を有し、凸部を挟み込むように第１の部材５０が形成されていてもよい。これにより、成形品を製造するための型の加工を簡略化させることができる。 This modified example is another example of a configuration in which one of the first and second members clamps the other without using a through hole provided in the first or second member. This can simplify the processing of the mold for manufacturing the compound gear 10, which is a molded product. Note that while Figures 23(a) to (g) show an example in which the first member 50 has a recess 55u and a protrusion 55p, the inner circumference of the second member 30 may have a recess and a protrusion, and the first member 50 may be formed to sandwich the protrusion. This can simplify the processing of the mold for manufacturing the molded product.

以下では、実施例１～７として、図１（ａ）～図６（ｃ）に示した構成、および図７（ａ）～図１２（ｂ）、図２０（ａ）～図２３（ｇ）に示した変形例の構成を持つ複合歯車の性能、ないし特性に関する評価結果につき説明する。 Below, we will explain the results of evaluation of the performance and characteristics of compound gears having the configurations shown in Figures 1(a) to 6(c) and the modified configurations shown in Figures 7(a) to 12(b) and Figures 20(a) to 23(g) as Examples 1 to 7.

＜実施例１＞
以下では、実施例１の歯車と、比較例１及び２の複合歯車において、第１の部材５０と第２の部材３０の収縮率に大きな差が生じた場合の耐久時間を評価する。実施例１の構成は、図１（ａ）～図３（ｃ）に示した複合歯車である。第１の部材５０にはポリブタジエンテレフタレート樹脂（ガラス繊維を３０％含有）を、また、第２の部材３０はポリアセタール樹脂（コポリマー）を用いている。第２の部材３０の歯部３１（噛合歯）はモジュールｍ＝０．５、圧力角２０°、歯数は９１、ねじれ角β＝２０°、歯幅ｔ＝１０ｍｍで形成している。複合歯車は、図４に示すような金型を用いて、第１の部材を成形した後に第２の部材を成形した。 Example 1
In the following, the durability time of the gear of Example 1 and the compound gears of Comparative Examples 1 and 2 when there is a large difference in the shrinkage rate between the first member 50 and the second member 30 is evaluated. The configuration of Example 1 is the compound gear shown in Figs. 1(a) to 3(c). The first member 50 is made of polybutadiene terephthalate resin (containing 30% glass fiber), and the second member 30 is made of polyacetal resin (copolymer). The teeth 31 (engagement teeth) of the second member 30 are formed with a module m = 0.5, a pressure angle of 20°, 91 teeth, a helix angle β = 20°, and a tooth width t = 10 mm. The compound gear was formed by molding the first member and then the second member using a mold as shown in Fig. 4.

下表１は、比較例１および２、実施例１の歯車を８０°Cおよび１２０°C高温炉に投入・保管し、クラックが生じるまでの経過時間を測定した結果である。また、回転伝達誤差（トルク０．１Ｎ・ｍ、回転速度２５ｒｐｍ駆動時の１歯成分の伝達誤差）測定を行った。 Table 1 below shows the results of measuring the time elapsed until cracks occurred when the gears of Comparative Examples 1 and 2 and Example 1 were placed in and stored in high-temperature furnaces at 80°C and 120°C. In addition, the rotational transmission error (transmission error of one tooth component when driven at a torque of 0.1 Nm and a rotational speed of 25 rpm) was measured.

Figure 0007483505000002
Figure 0007483505000002

比較例１は図１３（ａ、ｂ）に示すような従来の樹脂歯車の例であり、ポリアセタール（ＰＯＭ）樹脂のみで形成されている。比較例２は、図１４（ａ）～図１５（ｃ）で説明した構成の複合歯車であり、実施例１と同じ材料構成で第１の部材と第２の部材が形成されている。 Comparative Example 1 is an example of a conventional resin gear as shown in Figures 13(a, b), and is made only of polyacetal (POM) resin. Comparative Example 2 is a compound gear with the configuration described in Figures 14(a) to 15(c), and the first and second members are made of the same material configuration as in Example 1.

表１に示したように、従来構成の比較例１、比較例２と、実施例１を比較すると回転伝達誤差に大きな差異がみられ、比較例１の誤差が大きい結果となった。これは、比較例１の歯車では回転支持部と歯車部両方とも同一の材料を使用しており、比較的剛性の弱いポリアセタールを用いたため、回転駆動時のトルクによって歯車が変形してしまったためと考えられる。一方、比較例２と実施例１は複合材料で形成されているため部品剛性が強く、回転伝達誤差が良好である。 As shown in Table 1, when comparing Example 1 with Comparative Example 1 and Comparative Example 2, which have conventional configurations, a large difference was observed in the rotational transmission error, with Comparative Example 1 resulting in a large error. This is thought to be because the gear in Comparative Example 1 uses the same material for both the rotation support section and the gear section, and polyacetal, which has a relatively low rigidity, was used, causing the gear to deform due to the torque during rotational drive. On the other hand, Comparative Example 2 and Example 1 are formed from a composite material, so the parts have high rigidity and the rotational transmission error is good.

しかしながら、高温環境下の耐久時間では比較例２と実施例１よりも比較例１のほうが長く、有利であることが確認された。これは比較例１が同一材料のみで形成されているため、収縮差による歪が生じないためであることが考えられる。それでも、比較例１では８０°C環境で１３２３０時間、１２０°C環境では１８２５時間でクラックが生じている。これは歪による破断ではなく、高温環境下でエージングしたことによる材料分子鎖の伸びや切断・縮合によって機械的強度が低下したことに原因があると考えられる。これに対し、第２の部材３０の収縮を吸収する構造を持たない比較例２の耐久時間は著しく短い。これは複合歯車を構成する第２の部材と第１の部材との複合材料の収縮差から歪が発生したためである、と考えられる。一方、実施例１も複合材から形成されているが、比較例１より劣るものの、ほぼ同等の耐久時間が得られている。これは、実施例１では、貫通穴５７の内周側や第１の部材５０の外周側に第２の部材３０の収縮を吸収する空間を有しているために、歪の発生が最小限に抑えられているものと推測できる。 However, it was confirmed that Comparative Example 1 has a longer durability in a high-temperature environment than Comparative Example 2 and Example 1, and is more advantageous. This is thought to be because Comparative Example 1 is made of only the same material, and therefore distortion due to shrinkage difference does not occur. Nevertheless, Comparative Example 1 cracks after 13,230 hours in an 80°C environment and 1,825 hours in a 120°C environment. This is thought to be due to a decrease in mechanical strength due to elongation, cutting, and condensation of the material molecular chains caused by aging in a high-temperature environment, rather than fracture due to distortion. In contrast, Comparative Example 2, which does not have a structure to absorb the shrinkage of the second member 30, has a significantly shorter durability. This is thought to be due to distortion caused by the shrinkage difference between the composite material of the second member and the first member that constitute the compound gear. On the other hand, Example 1 is also made of a composite material, and although it is inferior to Comparative Example 1, it has an almost equal durability. This can be presumed to be because Example 1 has spaces on the inner periphery side of the through hole 57 and the outer periphery side of the first member 50 that absorb the shrinkage of the second member 30, thereby minimizing the occurrence of distortion.

図１６（ａ）、（ｂ）は、比較例２と実施例１の二つの複合歯車に対し、回転軸部を構成する第１の部材が０．１３％、外周側の第２の部材が０．３６％の収縮が発生したと仮定した時に第２の部材で生じる応力の解析結果である。図１６（ａ）が比較例２、図１６（ｂ）が実施例１の解析結果に相当し、応力の大きい部分が淡色で、応力の小さい部分が濃色で表現されている。図１６（ａ）、（ｂ）を比較して明らかなように、図１６（ａ）の比較例２では大きな応力が生じていることが分かる。応力が最も発生している部位は第１の部材の凹凸部６７（図１４（ａ））と対応している。つまり、回転方向のアンカーとして設けた凹凸部６７の形状が、収縮作用によって応力を発生させてしまうことが示されている。一方、実施例１によれば、上記の収縮を吸収する空間が設けられているために、第２の部材に収縮が生じても応力が生じないことが判る。 16(a) and (b) show the analysis results of the stress generated in the second member for the two compound gears of Comparative Example 2 and Example 1, assuming that the first member constituting the rotating shaft shrinks by 0.13% and the second member on the outer periphery shrinks by 0.36%. FIG. 16(a) corresponds to the analysis results of Comparative Example 2, and FIG. 16(b) corresponds to the analysis results of Example 1, in which the parts with high stress are shown in light colors and the parts with low stress are shown in dark colors. As is clear from a comparison between FIG. 16(a) and (b), it can be seen that a large stress is generated in Comparative Example 2 of FIG. 16(a). The part where the most stress is generated corresponds to the uneven portion 67 of the first member (FIG. 14(a)). In other words, it is shown that the shape of the uneven portion 67 provided as an anchor in the rotation direction generates stress due to the shrinkage action. On the other hand, according to Example 1, it can be seen that no stress is generated even if the second member shrinks because a space is provided to absorb the above-mentioned shrinkage.

＜実施例２＞
以下では、実施例１の複合歯車、図７（ｂ）の複合歯車（実施例２－１）、図７（ｃ）の複合歯車（実施例２－２）、従来の複合歯車（比較例２：上記の比較例２と同様）の評価結果を示す。実施例２－１、２－２の各部の材料と、歯車緒元は上記の実施例１と同一であるが、図７（ｂ）、（ｃ）のように貫通穴の側縁部が歯車中心の放射方向から傾いている点が異なる。実施例２－１は貫通穴の側縁部を－１０°（図７（ｂ））、実施例２－２は貫通穴の側縁部を＋１０°（図７（ｃ））だけ、それぞれ放射（直径）方向から傾斜させた構造である。なお、実施例１の貫通穴の側縁部は歯車中心の放射方向に沿って延びる構造である。 Example 2
The following describes the evaluation results of the compound gear of Example 1, the compound gear of FIG. 7(b) (Example 2-1), the compound gear of FIG. 7(c) (Example 2-2), and a conventional compound gear (Comparative Example 2: similar to the above Comparative Example 2). The materials of the various parts and the gear specifications of Examples 2-1 and 2-2 are the same as those of Example 1, but they are different in that the side edges of the through holes are inclined from the radial direction of the gear center as shown in FIGS. 7(b) and 7(c). Example 2-1 has a structure in which the side edges of the through holes are inclined from the radial (diameter) direction by −10° (FIG. 7(b)), and Example 2-2 has a structure in which the side edges of the through holes are inclined by +10° (FIG. 7(c)). Note that the side edges of the through holes of Example 1 extend along the radial direction of the gear center.

下表２は、比較例２と実施例１、２－１および２－２の複合歯車を８０°Cおよび１２０°C高温炉に投入・保管し、クラックが生じるまでの経過時間を評価した結果である。また、常温常湿環境（２３°C－５０％）下で１年間保管した後の回転伝達誤差（トルク０．１Ｎ・ｍ、回転速度２５ｒｐｍ駆動時の１歯成分の伝達誤差）も測定している。 Table 2 below shows the results of evaluating the time elapsed until cracks occurred when compound gears of Comparative Example 2 and Examples 1, 2-1, and 2-2 were placed in and stored in high-temperature furnaces at 80°C and 120°C. In addition, the rotational transmission error (transmission error of one tooth component when driven at a torque of 0.1 Nm and a rotational speed of 25 rpm) was also measured after one year of storage in a normal temperature and humidity environment (23°C-50%).

Figure 0007483505000003
Figure 0007483505000003

表２に示すように、従来構成の比較例２と実施例２－１および２－２を比較すると、実施例２－１および２－２では耐久時間が著しく向上していることが分かる。特に実施例２－１は実施例１と比較しても耐久時間に優れている。しかしながら、特に実施例２－１の１年後の回転伝達誤差は実施例１よりも若干悪化している。一方、実施例２－２の耐久時間も向上していることを確認したが、実施例１よりはやや耐久時間は落ちている（８０°Ｃ）。しかしながら、実施例２－２の１年後の回転誤差は実施例１よりも良好であり、精度が高い。これらの結果から実施例１（貫通穴の側縁部は回転軸を中心とした放射方向に沿っている）では、第２の部材の収縮に異方性がある、と考えられる。例えば、内径方向の収縮率が周方向の収縮率よりも小さいと、周方向において第１と第２の部材間に隙間が生じる。このような状態では歪は生じにくくなるが、回転伝達誤差は隙間の影響で悪化する。そして、実施例２－１では側縁部の傾斜が－１０°と負に設定されているため、隙間がより大きく生じ、耐久時間は向上したのに対して回転伝達誤差が悪化したと考えられる。一方、実施例２－２は側縁部の傾斜が＋１０°と正に設定されているため、隙間が生じない替わりに歪が多少発生するため、耐久時間がやや低下して回転伝達誤差は良化したと考えられる。 As shown in Table 2, when comparing Comparative Example 2 of the conventional configuration with Examples 2-1 and 2-2, it can be seen that the durability time is significantly improved in Examples 2-1 and 2-2. In particular, Example 2-1 has a superior durability time compared to Example 1. However, the rotation transmission error after one year in Example 2-1 is slightly worse than that in Example 1. On the other hand, it was confirmed that the durability time of Example 2-2 is also improved, but the durability time is slightly lower than that of Example 1 (80°C). However, the rotation error after one year in Example 2-2 is better than that of Example 1, and the accuracy is high. From these results, it is considered that there is anisotropy in the contraction of the second member in Example 1 (the side edge of the through hole is along the radial direction centered on the rotation axis). For example, if the contraction rate in the inner diameter direction is smaller than the contraction rate in the circumferential direction, a gap is generated between the first and second members in the circumferential direction. In such a state, distortion is less likely to occur, but the rotation transmission error is worsened due to the influence of the gap. In Example 2-1, the inclination of the side edge is set to a negative value of -10°, which is thought to have created a larger gap and improved durability while worsening the rotational transmission error. On the other hand, in Example 2-2, the inclination of the side edge is set to a positive value of +10°, which is thought to have created no gap but generated some distortion, resulting in a slight decrease in durability while improving the rotational transmission error.

以上の評価結果から、貫通穴の側縁部の傾斜角度は、第２の部材の収縮率、あるいはさらに回転伝達誤差や耐久性のいずれを優先するかによって、選択できることが判る。例えば複合歯車は回転伝達誤差を優先するか、あるいは耐久性を優先するかは、用途によって変わるため、適宜選択できるのが好ましい。例えば、内径方向の収縮率が周方向の収縮率よりも小さい場合では、回転伝達精度を得るためには側縁部の傾斜を負に、耐久性を得るためには側縁部の傾斜を正に設定することが考えられる。また、内径方向の収縮率が周方向の収縮率よりも大きい場合では、回転伝達精度を得るためには側縁部の傾斜を正に、耐久性を得るためには側縁部の傾斜を負に設定することが考えられる。 From the above evaluation results, it can be seen that the inclination angle of the side edge of the through hole can be selected depending on whether the shrinkage rate of the second member, or further the rotational transmission error or durability is prioritized. For example, in a compound gear, whether to prioritize the rotational transmission error or the durability varies depending on the application, so it is preferable to be able to select appropriately. For example, when the shrinkage rate in the inner diameter direction is smaller than the shrinkage rate in the circumferential direction, it is possible to set the inclination of the side edge negative to obtain rotational transmission accuracy, and positive to obtain durability. Also, when the shrinkage rate in the inner diameter direction is larger than the shrinkage rate in the circumferential direction, it is possible to set the inclination of the side edge positive to obtain rotational transmission accuracy, and negative to obtain durability.

＜実施例３＞
以下では、実施例３の複合歯車（図８（ａ～ｃ））と、比較例２（図１４（ａ、ｂ））の複合歯車の評価につき説明する。実施例３の各部の材料と、歯車緒元は上記の実施例１と同一であるが、実施例３の複合歯車は、図８（ａ～ｃ）に示すように第１の部材の内側ウェブには内側に向かって、厚みが漸減（減肉）するように０．５°の勾配がつけてある。下表３は、比較例２と実施例１および３の複合歯車を８０°Cおよび１２０°C高温炉に投入・保管し、クラックが生じるまでの経過時間を調査した結果を示している。 Example 3
Below, evaluations of the compound gear of Example 3 (Figs. 8(a-c)) and the compound gear of Comparative Example 2 (Figs. 14(a,b)) will be described. The materials of each part and the gear specifications of Example 3 are the same as those of Example 1 above, but in the compound gear of Example 3, the inner web of the first member has a gradient of 0.5° so that the thickness gradually decreases (thinning) toward the inside, as shown in Figs. 8(a-c). Table 3 below shows the results of storing the compound gears of Comparative Example 2 and Examples 1 and 3 in high-temperature furnaces at 80°C and 120°C, and investigating the elapsed time until cracks occurred.

Figure 0007483505000004
Figure 0007483505000004

表３に示すように、従来構成の比較例２と実施例１、実施例３を比較すると、実施例３の耐久時間が著しく向上していることが判る。即ち、第２の部材３０が肉厚方向に収縮しても、その分、第１の部材５０の内側ウェブが減肉しているため、内径方向への収縮が阻害されにくくなり、歪の発生が抑制される作用が認められる。 As shown in Table 3, when comparing Comparative Example 2 of the conventional configuration with Examples 1 and 3, it can be seen that the durability time of Example 3 is significantly improved. In other words, even if the second member 30 shrinks in the thickness direction, the inner web of the first member 50 is reduced in thickness by that amount, so shrinkage in the inner diameter direction is less likely to be hindered, and the occurrence of distortion is suppressed.

＜実施例４＞
以下では、図９（ａ～ｃ）の構成を有する複合歯車（実施例１、実施例４）と、従来の複合歯車（上記の比較例２）の評価につき説明する。下表４は、図９（ａ～ｃ）の構成を有する複合歯車（実施例１、実施例４）と、従来の複合歯車（上記の比較例２）の回転伝達誤差（トルク０．１Ｎ・ｍ、回転速度２５ｒｐｍ駆動時の１歯成分の伝達誤差）の比較結果を示している。実施例４の各部の材料と歯車緒元、およびウェブ形状は実施例１と同一であるが、実施例４では、図９に示すように第２の部材を射出するゲートが第１の部材の貫通穴上の位置に配設されている。 Example 4
Below, evaluations of the compound gears (Examples 1 and 4) having the configurations shown in Figures 9(a) to 9(c) and the conventional compound gear (Comparative Example 2 above) will be described. Table 4 below shows the results of a comparison of the rotational transmission error (transmission error of one tooth component when driven at a torque of 0.1 Nm and a rotational speed of 25 rpm) between the compound gears (Examples 1 and 4) having the configurations shown in Figures 9(a) to 9(c) and the conventional compound gear (Comparative Example 2 above). The materials and gear specifications of each part of Example 4, as well as the web shape, are the same as those of Example 1, but in Example 4, the gate for injecting the second member is disposed at a position above the through hole of the first member, as shown in Figure 9.

Figure 0007483505000005
Figure 0007483505000005

従来構成の比較例２と実施例１および４を比較すると、回転伝達誤差は実施例４において大きく改善されている。これは第２の部材を射出ゲートが、第１の部材の貫通穴上に配設されているため射出成形に伴う圧力を第１の部材が受けにくく、変形しにくくなった結果、と考えられる。 Comparing Comparative Example 2, which has a conventional configuration, with Examples 1 and 4, the rotational transmission error is greatly improved in Example 4. This is thought to be because the injection gate for the second member is disposed above the through hole of the first member, so the first member is less likely to be subjected to the pressure associated with injection molding and is less likely to deform.

＜実施例５＞
以下では、図１０（ａ、ｂ）の構成を有する複合歯車（実施例５）、上記の実施例１、および従来の複合歯車（上記の比較例２）の評価につき説明する。 Example 5
In the following, evaluations of the compound gear having the configuration shown in Figs. 10(a) and 10(b) (Example 5), the above Example 1, and the conventional compound gear (the above Comparative Example 2) will be described.

表５は、図１０（ａ、ｂ）の構成を有する実施例５の複合歯車、上記の実施例１、および従来の複合歯車（上記の比較例２）の比較結果を示している。実施例５の各部の材料と、歯車緒元は上記の実施例１と同一であるが、図１０（ａ、ｂ）に示すように第１の部材の貫通穴の隅部、特に内周側の隅部を曲線形状（円筒面、面取り）で構成されている。表５は、比較例２と実施例１および５の複合歯車のＣＡＤモデルに対して、トルク０．１Ｎ・ｍで回転駆動させた際、第１の部材で生じる最大主応力（ＭＰａ）の解析結果に相当する。 Table 5 shows the results of a comparison between the compound gear of Example 5 having the configuration shown in Figure 10 (a, b), the above Example 1, and a conventional compound gear (Comparative Example 2 above). The materials of each part and the gear specifications of Example 5 are the same as those of Example 1 above, but as shown in Figure 10 (a, b), the corners of the through hole of the first member, especially the corners on the inner circumference side, are configured with a curved shape (cylindrical surface, chamfer). Table 5 corresponds to the analysis results of the maximum principal stress (MPa) generated in the first member when the CAD models of the compound gears of Comparative Example 2 and Examples 1 and 5 are rotated and driven at a torque of 0.1 Nm.

Figure 0007483505000006
Figure 0007483505000006

従来構成の比較例２と、実施例１および５を比較すると、実施例１では比較例２よりも大きな主応力が生じているが、実施例５は比較例２よりも小さな主応力となっている。ここで、図１７は実施例１の解析結果であり、複合歯車を反時計回りにトルクを付加した際に第１の部材で生じる応力分布を示している。図１７に示されるように、貫通穴の隅部において応力が大きく生じていることが判る。これは所謂、ノッチ効果と呼ばれる作用であり、実施例１の貫通穴の隅部のような部位には応力集中しやすくなる傾向がある。しかしながら、実施例５、即ち図１０（ａ、ｂ）のように応力集中しやすい貫通穴の隅部を曲線形状、例えば円筒面や面取りの形状を付加するだけで、表５に示したように応力を分散させ、主応力を低減させる作用がある。 Comparing Comparative Example 2, which has a conventional configuration, with Examples 1 and 5, Example 1 generates a larger principal stress than Comparative Example 2, but Example 5 generates a smaller principal stress than Comparative Example 2. Here, FIG. 17 is the analysis result of Example 1, and shows the stress distribution generated in the first member when a torque is applied to the compound gear in the counterclockwise direction. As shown in FIG. 17, it can be seen that a large stress is generated at the corners of the through hole. This is the so-called notch effect, and there is a tendency for stress to concentrate easily in areas such as the corners of the through hole in Example 1. However, in Example 5, that is, in FIG. 10 (a, b), simply adding a curved shape, such as a cylindrical surface or a chamfered shape, to the corners of the through hole where stress is likely to concentrate can disperse stress as shown in Table 5 and reduce the principal stress.

＜実施例６＞
以下では、図１１（ａ～ｃ）のように構成した実施例６の複合歯車と、上記の実施例１および比較例２の複合歯車の評価につき説明する。実施例６の複合歯車では、各部の材料と、歯車緒元は上記の実施例１と同一であるが、図１１（ａ～ｃ）のように第１の部材５０の内側ウェブ５５の外周部にリング状に突条ｄを設けてある。 Example 6
11(a) to 11(c), and the compound gears of Example 1 and Comparative Example 2 are evaluated below. The compound gear of Example 6 is made of the same materials as Example 1 and has the same gear specifications as Example 1, but has a ring-shaped ridge d on the outer periphery of the inner web 55 of the first member 50 as shown in FIG.

表６は、図１１（ａ～ｃ）の構成を有する実施例６の複合歯車、上記の実施例１、および従来の複合歯車（上記の比較例２）の比較結果を示している。評価は耐久時間（ｈｒ）で、この耐久時間（ｈｒ）は比較例２と実施例１および６の複合歯車を８０°Cおよび１２０°C高温炉に投入・保管し、クラックが生じるまでの経過時間に相当する。 Table 6 shows the results of a comparison between the compound gear of Example 6 having the configuration shown in Figures 11 (a-c), the above Example 1, and the conventional compound gear (Comparative Example 2 above). Evaluation was based on durability time (hr), which corresponds to the elapsed time until cracks appeared when the compound gears of Comparative Example 2, Examples 1, and 6 were placed in and stored in high-temperature furnaces at 80°C and 120°C.

Figure 0007483505000007
Figure 0007483505000007

従来構成の比較例２と実施例１および６を比較すると、特に実施例６において耐久時間が向上している。これは、実施例６の第１の部材の内側ウェブ外周にリング状に突条ｄを設けることにより、第１の部材の外径に第２の部材が形成されにくくなった結果、と考えてよい。この例では第２の部材にはポリアセタール樹脂を用いているが、通常の射出成形では１０μｍほどの空間があれば樹脂が流入する傾向がある。実施例１は実施例６のような突条を欠いており、第１の部材が形成されてから第２の部材が形成されるまでに第１の部材自体が収縮し、金型と第１の部材間に若干の隙間が形成されてしまっている可能性がある。このような場合、第１の部材の外周部に微小な第２の部材の材料が流入してしまう。第２の部材が第１の部材の外周部に形成されると第２の部材の収縮を吸収するための空間が減り、第２の部材の収縮を阻害し、割れなどの破損に関する耐久時間が低下する。しかしながら、実施例６では突条ｄ（図１１（ａ～ｃ））がこの流入をせき止める作用を発揮し、第２の部材の収縮を吸収するための空間を確保でき、割れのような破損に対する耐久時間を向上させることができるようになる。 Comparing Comparative Example 2 of the conventional configuration with Examples 1 and 6, the durability time is particularly improved in Example 6. This can be considered as a result of the provision of a ring-shaped protrusion d on the outer periphery of the inner web of the first member in Example 6, which makes it difficult for the second member to be formed on the outer diameter of the first member. In this example, polyacetal resin is used for the second member, but in normal injection molding, resin tends to flow in if there is a space of about 10 μm. Example 1 lacks the protrusions like Example 6, and the first member itself may shrink between the formation of the first member and the formation of the second member, resulting in the formation of a slight gap between the mold and the first member. In such a case, minute amounts of material of the second member flow into the outer periphery of the first member. When the second member is formed on the outer periphery of the first member, the space for absorbing the shrinkage of the second member is reduced, which inhibits the shrinkage of the second member and reduces the durability time regarding damage such as cracking. However, in Example 6, the protrusion d (Figures 11(a-c)) acts to block this inflow, ensuring space to absorb the shrinkage of the second member and improving the durability against damage such as cracks.

＜実施例７＞
以下では、図２０（ａ、ｂ）のように構成した複合歯車（実施例７）と、上記の実施例１の複合歯車の評価につき説明する。実施例７（ａ、ｂ）の複合歯車では、各部の材料と、歯車緒元は上記の実施例１と同一であるが、図２０（ａ、ｂ）のように内側ウェブ上の貫通穴の側縁部のなす角φを実施例１よりも大きくしている。言い換えると、周方向において貫通穴が設けられている領域の比率が、実施例１よりも大きい構成としている。 Example 7
Below, evaluations of a compound gear (Example 7) configured as shown in Figures 20(a, b) and the compound gear of Example 1 above will be described. In the compound gear of Example 7(a, b), the materials of each part and the gear specifications are the same as those of Example 1 above, but the angle φ formed by the side edges of the through holes on the inner web is made larger than that of Example 1, as shown in Figures 20(a, b). In other words, the proportion of the area in the circumferential direction where through holes are provided is larger than that of Example 1.

表７は、図２０（ａ、ｂ）の構成を有する実施例７の複合歯車、上記の実施例１の複合歯車の比較結果を示している。評価は第２の部材成形による、第１の部材の内側ウェブの変形で、充填完了時点での変形量の解析結果(μm)に相当する。 Table 7 shows the results of a comparison between the compound gear of Example 7 having the configuration shown in Figure 20 (a, b) and the compound gear of Example 1 above. The evaluation is the deformation of the inner web of the first component due to molding of the second component, and corresponds to the analysis result (μm) of the amount of deformation at the time of completion of filling.

Figure 0007483505000008
Figure 0007483505000008

実施例１と実施例７を比較すると、実施例７において内側ウェブの変形が抑制されている。これは側縁部のなす角を大きくすることで、第２の部材を成形する際に生じる圧力が緩和された結果である。ウェブの剛性としては低下していることが考えられるが、剛性低下の影響以上に圧力緩和の影響が大きく効いた結果であるといえる。 Comparing Example 1 and Example 7, deformation of the inner web is suppressed in Example 7. This is the result of reducing the pressure generated when molding the second component by increasing the angle of the side edges. It is thought that the rigidity of the web has decreased, but this is the result of the effect of pressure reduction being greater than the effect of the reduced rigidity.

１…成形型（金型）、２…第１の固定金型、第２の固定金型（金型）、４…移動駒（移動金型）、１０～１５、４０…複合歯車、３０、９０…第２の部材、３１…歯部、３２、９２…外側ウェブ、５０、６０、７４…第１の部材、５１、６１…回転支持部、５５、６５…内側ウェブ、５７…貫通穴、５７ａ…内周縁部、５７ｂ…外周縁部、５８…側縁部。 1...Mold (mold), 2...First fixed mold, second fixed mold (mold), 4...Moving piece (moving mold), 10-15, 40...Compound gear, 30, 90...Second member, 31...Tooth portion, 32, 92...Outer web, 50, 60, 74...First member, 51, 61...Rotational support portion, 55, 65...Inner web, 57...Through hole, 57a...Inner peripheral edge, 57b...Outer peripheral edge, 58...Side edge.

Claims (18)

回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材と、
外周に少なくとも一つ以上の噛合歯を有し、前記ウェブに支持されて前記第１の部材の外周を囲むように設けられている第２の部材と、を備えた複合歯車であって、
前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように形成されている、複合歯車。 A first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion;
a second member having at least one meshing tooth on an outer periphery thereof, the second member being supported by the web and provided to surround an outer periphery of the first member,
a compound gear formed so that an outermost peripheral surface of the first member has a radial space between it and the second member, an innermost peripheral surface of the second member has a radial space between it and the first member, and at least one of the first member and the second member holds the other of the first member and the second member from both axial sides of the rotating shaft portion. 前記第２の部材は、前記第１の部材の一部を前記軸方向の両側から挟持する挟持部を有する、請求項１に記載の複合歯車。 The compound gear according to claim 1, wherein the second member has a clamping portion that clamps a portion of the first member from both sides in the axial direction. 前記ウェブの前記挟持部によって挟持される部分が、外周から前記回転軸部に向かうにつれて、前記軸方向の厚みが漸減するよう形成されている、請求項２に記載の複合歯車。 The compound gear according to claim 2, wherein the portion of the web that is clamped by the clamping portion is formed so that the thickness in the axial direction gradually decreases from the outer periphery toward the rotating shaft portion. 前記第１の部材の前記ウェブには、軸方向に貫通する貫通穴が設けられ、
前記第２の部材は、前記貫通穴を貫通するように形成され、
前記第１の部材が第１の樹脂材料から成り、前記第２の部材が第２の樹脂材料から成り、前記第１の樹脂材料が前記第２の樹脂材料よりも高剛性であり、
前記第１の部材及び前記第２の部材を一体化するように成形済みの前記第１の部材に対して前記第２の樹脂材料が射出されたゲートのゲート痕を前記第１の部材の前記貫通穴の位置に備えた請求項１に記載の複合歯車。 The web of the first member is provided with a through hole passing therethrough in the axial direction,
The second member is formed to pass through the through hole,
the first member is made of a first resin material, the second member is made of a second resin material, and the first resin material has a higher rigidity than the second resin material;
2. The compound gear according to claim 1, wherein a gate mark of a gate through which the second resin material is injected into the first member that has been molded to integrate the first member and the second member is provided at a position of the through hole of the first member. 前記第１の部材の前記ウェブの外周に突条が形成されている請求項１に記載の複合歯車。 The compound gear according to claim 1, wherein a ridge is formed on the outer periphery of the web of the first member. 前記第１の部材及び前記第２の部材の前記他方は、前記回転軸部の周方向に対向する２つの側縁部を含む貫通穴を備え、
前記第１の部材及び前記第２の部材の前記一方は、前記貫通穴を貫通するように形成されている、請求項１に記載の複合歯車。 the other of the first member and the second member has a through hole including two side edge portions opposed to each other in a circumferential direction of the rotating shaft portion,
The compound gear according to claim 1 , wherein said one of said first member and said second member is formed to pass through said through hole. 前記側縁部の各々は、前記軸方向に見て直線状に延びており、前記回転軸部の径方向に対して－１０°から＋１０°の範囲の傾斜角度を有する、請求項６に記載の複合歯車。 The compound gear according to claim 6, wherein each of the side edges extends linearly when viewed in the axial direction and has an inclination angle in the range of -10° to +10° with respect to the radial direction of the rotating shaft portion. 前記貫通穴は、前記第１の部材に設けられ、前記貫通穴は、２つの前記側縁部と、前記貫通穴の外周側および内周側において、２つの前記側縁部を繋ぐ外周縁部と、内周縁部と、により画成される、請求項７に記載の複合歯車。 The compound gear according to claim 7, wherein the through hole is provided in the first member, and the through hole is defined by the two side edges, and an outer peripheral edge connecting the two side edges on the outer peripheral side and the inner peripheral side of the through hole, and an inner peripheral edge. 前記外周縁部および／または前記内周縁部が曲線形状を有する、請求項８に記載の複合歯車。 The compound gear according to claim 8, wherein the outer peripheral edge and/or the inner peripheral edge has a curved shape. 前記側縁部と、前記外周縁部および／または前記内周縁部と、が曲線形状を有する隅部を介して連続している、請求項８に記載の複合歯車。 The compound gear according to claim 8, wherein the side edge portion is continuous with the outer peripheral edge portion and/or the inner peripheral edge portion via a corner portion having a curved shape. 前記隅部の曲線形状が、円筒面または面取りである、請求項１０に記載の複合歯車。 The compound gear according to claim 10, wherein the curved shape of the corner is a cylindrical surface or a chamfer. 前記貫通穴の２つの前記側縁部のなす角φ（度）が以下を満たす複合歯車であって、
Figure 0007483505000009
 ただし、ｌ［ｍｍ］は前記第１の部材の最外周面から前記貫通穴の外周縁部までの長さ、ｔ［ｍｍ］は前記第１の部材の前記ウェブの厚みを示す、請求項６に記載の複合歯車。 A compound gear in which an angle φ (degrees) between the two side edges of the through hole satisfies the following:
Figure 0007483505000009
 The compound gear according to claim 6, wherein l [mm] is a length from an outermost surface of the first member to an outer circumferential edge of the through hole, and t [mm] is a thickness of the web of the first member. 前記第１の部材は、前記第２の部材の一部を前記軸方向の両側から挟持する挟持部を有する、請求項１に記載の複合歯車。 The compound gear according to claim 1, wherein the first member has a clamping portion that clamps a portion of the second member from both sides in the axial direction. 前記第１の部材は、前記第２の部材の一部を前記軸方向の両側から挟持する第１挟持部を有し、前記第２の部材は、前記第１の部材の一部を前記軸方向の両側から挟持する第２挟持部を有する、請求項１に記載の複合歯車。 The compound gear according to claim 1, wherein the first member has a first clamping portion that clamps a portion of the second member from both sides in the axial direction, and the second member has a second clamping portion that clamps a portion of the first member from both sides in the axial direction. 感光ドラムと、
前記感光ドラムの長手方向の端部に取り付けられて前記感光ドラムに回転力を伝達する請求項１に記載の複合歯車と、を備えた画像形成装置用のカートリッジ。 A photosensitive drum;
2. A cartridge for an image forming apparatus comprising: the compound gear according to claim 1, which is attached to an end portion of the photosensitive drum in a longitudinal direction thereof and transmits a rotational force to the photosensitive drum. 請求項１５に記載のカートリッジと、前記カートリッジの前記感光ドラムを用いて画像形成を行う画像形成機構と、を備えた画像形成装置。 An image forming device comprising the cartridge according to claim 15 and an image forming mechanism that forms an image using the photosensitive drum of the cartridge. 複合歯車の製造に用いられる成形型において、
前記複合歯車は、
回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材と、
外周に少なくとも一つ以上の噛合歯を有し、前記ウェブに支持されて前記第１の部材の外周を囲むように設けられている第２の部材と、を備え、
前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように形成されており、
前記成形型は、第１の固定金型と、第２の固定金型と、移動金型と、を有し、前記移動金型が前記第１の固定金型に対向している状態で前記第１の部材が成形され、前記第１の部材が成形された後に前記移動金型が前記第２の固定金型に対向する位置に移動した状態で、前記第１の部材と一体になるように前記第２の部材が成形されるように構成されている、成形型。 In a molding tool used for manufacturing a compound gear,
The compound gear is
A first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion;
a second member having at least one meshing tooth on an outer periphery thereof, the second member being supported by the web and provided to surround the outer periphery of the first member;
an outermost peripheral surface of the first member has a radial space between it and the second member, an innermost peripheral surface of the second member has a radial space between it and the first member, and at least one of the first member and the second member is formed to sandwich the other of the first member and the second member from both sides in the axial direction of the rotating shaft portion,
The molding die has a first fixed die, a second fixed die, and a movable die, and is configured so that the first member is molded with the movable die facing the first fixed die, and after the first member is molded, the movable die moves to a position facing the second fixed die, and the second member is molded to be integral with the first member. 回転軸部と、前記回転軸部から径方向に広がる円盤状のウェブと、を有する第１の部材を成形する第１の工程と、
第１の工程で成形された前記第１の部材を成形型に収容し、外周に少なくとも一つ以上の噛合歯を有する第２の部材を、前記ウェブに支持されて前記第１の部材の外周を囲むように形成する第２の工程と、を含み、
前記第２の工程において、前記第１の部材の最外周面が前記第２の部材との間に径方向の空間を有し、前記第２の部材の最内周面が前記第１の部材との間に径方向の空間を有し、前記第１の部材及び前記第２の部材の少なくとも一方が、前記第１の部材及び前記第２の部材の他方を前記回転軸部の軸方向の両側から挟持するように、前記第２の部材を形成する複合歯車の製造方法。 A first step of molding a first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion;
a second step of placing the first member molded in the first step in a mold and forming a second member having at least one meshing tooth on an outer periphery thereof so as to be supported by the web and surround the outer periphery of the first member;
a second member formed on the outermost surface of the first member such that there is a radial space between the first member and the second member, an innermost surface of the second member such that there is a radial space between the first member and the second member, and at least one of the first member and the second member holds the other of the first member and the second member from both axial sides of the rotating shaft portion.
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JP2010125822A (en) 2008-12-01 2010-06-10 Tigers Polymer Corp Annular resin molded article
JP2010139041A (en) 2008-12-15 2010-06-24 Tigers Polymer Corp Synthetic resin gear
WO2011058701A1 (en) 2009-11-11 2011-05-19 本田技研工業株式会社 Worm wheel
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JP2001150491A (en) 1999-11-26 2001-06-05 Sanshu Fine Tool:Kk Method for dichroically molding and mold used therefor
JP2001315160A (en) 2000-05-09 2001-11-13 Showa Corp Method for manufacturing gear made of resin
JP2003021224A (en) 2001-07-06 2003-01-24 Asmo Co Ltd Gear and manufacturing method for the same
JP2010125822A (en) 2008-12-01 2010-06-10 Tigers Polymer Corp Annular resin molded article
JP2010139041A (en) 2008-12-15 2010-06-24 Tigers Polymer Corp Synthetic resin gear
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